JP2007251631A - Cache server apparatus for sophisticating recursive inquiry, cache control method, and program for cache server - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cache server which widely registers available cache data and efficiently utilizes the widely registered cache data. <P>SOLUTION: A data registration processing section widely registers a reply from a DNS server, received via a recursive inquiry processing section as cache data by associating the reply with reliability that is a newly introduced concept, in the case of a scene utilizing the registered cache data, a reply propriety discrimination section discriminates the cache data with a prescribed reply threshold value or over to be replyable, and a reply processing section is configured to utilize the cache data discriminated as replyable by the reply propriety discrimination section. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention stores an inquiry response to a DNS server device as cache data, and an immediate response to the DNS client device based on the cache data stored when a DNS query request is received from the DNS client device or the DNS server device The present invention relates to a cache server device, a cache control method, and a program for a cache server device that return any one of responses after a recursive inquiry is performed.

  Conventionally, in response to a name resolution request (hereinafter referred to as “DNS query request”) from a DNS (Domain Name System) client device such as a personal computer (PC), a response to an inquiry made to the DNS server device in the past is made. A cache server device that responds using stored cache data is known.

  For example, when the cache server apparatus receives a DNS query request for returning the IP address of the server A having the domain name “aaa.co.jp.”, the cache data includes the address information of the server A. If so, “response processing” using cache data is executed. On the other hand, if the address information of the server A is not included in the cache data, a “recursive query process” for the authoritative server (hereinafter referred to as “DNS server device”) is executed to acquire the address information of the server A. Then, perform name resolution and respond.

  Here, “recursive query processing” refers to query processing for DNS server devices that manage each domain hierarchy such as “root”, “jp.”, And “co.jp.” in order from the upper hierarchy. This refers to the process of acquiring address information for the target domain name.

  By the way, in a conventional cache server device, only a reliable answer (for example, an official answer from a DNS server device having jurisdiction over a domain zone) can be stored as cache data. There was something to do. That is, in such a conventional cache server, an answer that cannot be used for “response processing” (for example, a delegated answer indicating that the DNS server device under the hierarchy can resolve the name) has been discarded.

  Further, in Patent Document 1, a formal response cache area and a delegation answer cache area are provided so that a formal answer and a delegation answer are registered in each cache area, and the data structure of each cache area is different. Discloses a technique for speeding up the process of using cache data.

US Patent Application Publication No. 2004/0267907

  However, since the cache server device that discards the delegation response described above registers available cache data, there is a problem in that the process using the cache data cannot be performed efficiently. Specifically, even if a DNS server device capable of name resolution is indicated in the delegation answer, since this delegation answer is not cached, the DNS server apparatus in the upper hierarchy is used as the starting point for each inquiry. It was necessary to execute “recursive query processing”. Therefore, there has been a problem that even in the second and subsequent inquiries, the time required for the inquiry processing to the DNS server device cannot be shortened.

  Moreover, although the cache server apparatus disclosed in Patent Document 1 can perform cache data widely, there is a problem that processing when using registered cache data is complicated. Specifically, when “recursive query processing” is performed, it is necessary to refer widely to the address of the DNS server device that is the query destination, so both the cache area for formal answers and the cache area for delegated answers are referred to. This makes the reference process complicated. Further, if the data structure of each cache area is different, the processing procedure for referring to the cache data becomes complicated.

  Furthermore, the cache server device disclosed in Patent Document 1 has a fixed configuration in which a formal answer and a delegated answer are registered in a cache area provided for each answer, and the usage policy of the registered cache data There was also a problem that could not be changed flexibly.

  For these reasons, it is a big problem how to realize a cache server device that can register a wide range of usable cache data and can efficiently use the widely registered cache data.

  The present invention has been made to solve the above-described problems of the prior art, and can register a wide range of usable cache data and can efficiently use a wide range of cache data. It is an object to provide a cache server device, a cache control method, and a program for the cache server device.

  In order to solve the above-described problems and achieve the object, the invention according to claim 1 stores the query response to the DNS server device as cache data, and receives the DNS query request from the DNS client device. A cache server device that returns either an immediate response to the DNS client device based on cache data or a response after making a recursive query to the DNS server device, the query to the DNS server device A registration unit for registering the combined response with the reliability of the response and registering it as the cache data, and an availability determination for determining whether the cache data registered by the registration unit is available based on the reliability Means.

  The invention according to claim 2 further comprises response means for making an immediate response to the DNS client device based on a determination result of the availability determination means in the above invention, wherein the availability determination means Before the response means makes an immediate response to the DNS client device, it is determined that the cache data having the reliability equal to or higher than the response threshold can be used for an immediate response.

  In the invention according to claim 3, in the above invention, the registration unit uses a registration threshold having a value lower than the response threshold, and the reliability is equal to or higher than the registration threshold. The inquiry response is registered as the cache data.

  The invention according to claim 4 further comprises inquiry means for making a recursive inquiry to the DNS server device based on a determination result of the availability determination means in the above invention, wherein the availability determination is performed. The means uses an inquiry threshold having a value lower than the response threshold, and the reliability is inquired before the inquiry means makes a recursive inquiry to the DNS server device. It is determined that the cache data that is equal to or greater than the matching threshold can be used for recursive queries.

  The invention according to claim 5 is the above invention, further comprising cache data storage means having a cache area partitioned based on the reliability, wherein the registration means responds to an inquiry to the DNS server device. Is registered in each cache area corresponding to the reliability.

  According to a sixth aspect of the present invention, in the above invention, the data structure of the cache data registered by the registration means is a hash table, and a search algorithm for searching for the cache data is defined in the cache data. A search algorithm switching means for switching for each purpose of use is further provided.

  Further, the invention according to claim 7 is the above invention, wherein the registration means is provided when the reliability of the inquiry response to the DNS server device is different from the reliability of the cache data already registered. The cache data is updated using a simple response.

  In addition, the invention according to claim 8 accumulates the inquiry response to the DNS server device as cache data, and when the DNS query request is received from the DNS client device, the DNS client device is sent to the DNS client device based on the cache data. A cache control method for returning either an immediate response or a response after a recursive query to the DNS server device, wherein the query response to the DNS server device corresponds to the reliability of the response And a registration step of registering the cache data as the cache data, and an availability determination step of determining whether the cache data registered in the registration step is available based on the reliability.

  In addition, the invention according to claim 9 accumulates the inquiry response to the DNS server device as cache data, and when the DNS query request is received from the DNS client device, the DNS client device is sent to the DNS client device based on the cache data. A cache server device program that returns either an immediate response or a response after a recursive query to the DNS server device, wherein the query response to the DNS server device is a reliability of the response And causing the computer to execute a registration procedure for registering it as the cache data in association with the cache data, and an availability determination procedure for determining the availability of the cache data registered by the registration procedure based on the reliability. Features.

  According to the invention of claim 1, 8, or 9, the inquiry response to the DNS server apparatus is registered as cache data after being associated with the reliability of the response, and the availability of the registered cache data is set as the reliability. Since the determination is made based on this, it is possible to register a wide range of usable cache data and to efficiently use a wide range of registered cache data.

  According to the second aspect of the present invention, an immediate response to the DNS client device is made based on the determination result of the availability determination, and the reliability is a response threshold before making an immediate response to the DNS client device. Since the cache data is determined to be usable for an immediate response, the reliability of the response to the DNS client device can be easily ensured and flexible by changing the response threshold. There is an effect that operation can be performed.

  According to the invention of claim 3, a registration threshold having a value lower than the response threshold is used, and an inquiry response whose reliability is equal to or higher than the registration threshold is registered as cache data. Therefore, by using a registration threshold value lower than the response threshold value, it is possible to reduce the number of recursive queries to the DNS server device by registering a lot of cache data used for querying the DNS server device. By changing the registration threshold, there is an effect that flexible operation can be performed.

  According to the invention of claim 4, the inquiry threshold is determined to be recursively inquired to the DNS server device based on the determination result of the availability determination, and has a value lower than the response threshold. And before performing recursive queries to the DNS server device, it is determined that cache data whose reliability is greater than or equal to the query threshold can be used for recursive queries. In addition, the reliability of the inquiry to the DNS server device can be easily ensured, and flexible operation can be performed by changing the inquiry threshold.

  According to the invention of claim 5, the cache area divided according to the reliability is provided, and the inquiry response to the DNS server device is registered in each cache area corresponding to the reliability. By realizing the association between the cache data and the reliability by providing a cache area corresponding to the reliability, it is possible to improve the efficiency of the reference process when using the cache data.

  According to the invention of claim 6, since the cache data structure is a hash table and the search algorithm for searching for the cache data is switched for each use purpose of the cache data. By using a suitable search algorithm, it is possible to improve the efficiency of reference processing when using cache data.

  According to the invention of claim 7, when the reliability of the inquiry response to the DNS server device is different from the reliability of the already registered cache data, the cache data is updated using a new response. Therefore, it is possible to execute the use process such as the response process and the inquiry process by using the reliability updated to the latest state.

  Embodiments 1 and 2 of a cache server device to which a cache control method according to the present invention is applied will be described below in detail with reference to the accompanying drawings. In the first embodiment, a cache server apparatus that caches an answer received from a DNS server apparatus with reliability added thereto, and in a second embodiment, a cache server apparatus provided with a cache area corresponding to the reliability of the answer will be described. I decided to.

  In the first embodiment, a cache server device that caches an answer received from a DNS server device with reliability added will be described. FIG. 1 is a diagram illustrating an overview and features of the cache server device 10 according to the first embodiment. It is assumed that the cache server device 10 shown in the figure transmits / receives communication data to / from the DNS client device 110 and the DNS server device 120 via a network.

  As shown in FIG. 1, the cache server device 10 registers the response received from the DNS server device 120 in the cache area after associating it with the reliability of the response (see (3) in FIG. 1). The response function and the recursive query function are mainly characterized in that the cache data is used based on the reliability of the cache data (see (1) and (2) in FIG. 1).

  In other words, without unnecessarily discarding the response from the DNS server device 120, it is widely registered in association with the newly introduced concept "reliability" and used when using the registered cache data. Only cache data with reliability that meets the purpose is used. Therefore, it is possible to register a wide range of usable cache data and to efficiently use a wide range of cache data. A detailed description of “reliability” will be described later with reference to FIG.

  The processing procedure performed by the cache server device 10 will be described in chronological order as follows. That is, the response function that receives the DNS query request from the DNS client device 110 includes the query request target information in the cache data having a predetermined reliability (the reliability is 1 in FIG. 1) among the cache data in the cache area. It is determined whether or not. If the query request target information is included, a response is made to the DNS client device 110 using the corresponding cache data. If the query request information is not included, the recursive query function is requested to acquire the query request target information from the DNS server device 120.

  The recursive query function that receives the request from the response function creates an address list of the DNS server device 120 that is the query destination using the cache data (all reliability levels in FIG. 1), and each domain hierarchy Inquiries are repeated from the upper hierarchy to the lower hierarchy with respect to the DNS server apparatus 120 provided in FIG. When a response including desired information is received, the response is passed to the response function to cause the DNS client device 110 to respond, and cache data is registered so that the response received from the DNS server device 120 is registered in the cache area. Request registration process.

  The cache data registration process registers the response from the DNS server device 120 in the cache area after associating the response with the reliability of the response. Specifically, when the cache data registration process receives a response from the DNS server device 120 via the recursive query function, the reliability of each response is determined by confirming the content of the response. Then, cache data associated with the determined reliability is registered (see (3) in FIG. 1). That is, in the cache data registration process, even when the response from the DNS server device 120 has a reliability that cannot withstand the response to the DNS client device 110, the cache data registration process registers the cache data in association with the reliability.

  In this way, it is possible to register a lot of cache data that can be used by the recursive query function, and as a result, the processing time required for recursive queries can be shortened by reducing the number of recursive queries. It becomes. On the other hand, since the response function uses only the cache data registered in the cache area and having a predetermined reliability, the reliability of the response to the DNS client device 110 can be ensured.

  Here, an outline of a cache server device according to the prior art will be described with reference to FIG. FIG. 15 is a diagram showing an outline of a cache server device according to the prior art. As shown in the figure, in the cache server device according to the prior art, only the reliable data that can be used for the response to the DNS client device 110 is cached as cache data. With such a configuration, although the reliability of the response to the DNS client device 110 can be ensured, the cache data that can be used by the recursive query function decreases, resulting in the time required for the recursive query. There was a problem that could not be shortened.

  For example, when a delegation response is received from the DNS server device 120, the reliability of the delegation response is not worthy of a response to the DNS client device 110, and is therefore not discarded as a cache target. However, since this delegation answer includes information such as the address of the DNS server device 120 capable of name resolution, if it is discarded, it cannot be used for recursive queries.

  On the other hand, the cache server device 10 according to the first embodiment caches cache data having reliability that cannot be used for a response to the DNS client device 110 but can be used for an inquiry to the DNS server device 120. Therefore, it is often possible to directly query the DNS server device 120 capable of name resolution, and as a result, the number of queries can be reduced, so recursive querying is required. Processing time can be shortened.

  Next, the configuration of the cache server device 10 according to the first embodiment will be described with reference to FIG. FIG. 2 is a block diagram illustrating the configuration of the cache server device 10 according to the first embodiment. In the figure, only processing units necessary for explaining the features of the cache server device 10 are shown, and a processor such as a CPU (Central Processing Unit) and a process that functions as a general cache server are shown. The description about the part is omitted.

  As shown in FIG. 2, the cache server device 10 includes a control unit 11, a storage unit 12, and a communication processing unit 13. The control unit 11 further includes a response processing unit 11a, a response availability determination unit 11b, a recursive query processing unit 11c, and a data registration processing unit 11d, and the storage unit 12 stores the cache data 12a. is doing.

  The control unit 11 registers the response from the DNS server device 120 as the cache data 12a in association with the reliability, and when using the cache data 12a, determines whether the DNS data can be used based on the reliability. It is a processing unit that performs a response to the client device 110 or an inquiry to the DNS server device 120.

  The response processing unit 11a accepts a DNS query request from the DNS client device 110, and when the response data is included in the cache data 12a that the response availability determination unit 11b can use for the response, the response processing unit 11a It is a processing unit that performs a response process using information. The response processing unit 11a performs processing for requesting the recursive query processing unit 11c to make an inquiry to the DNS server device 120 when the cache data 12a does not include response information. But there is.

  The response availability determination unit 11b refers to the reliability associated with each cache data 12a, for example, the cache data 12a having a reliability equal to or higher than a predetermined response threshold for response to the DNS client device 110. The processing unit determines that the cache data 12a can be used. The response availability determination unit 11b also performs processing for notifying the response processing unit 11a of the determination result.

  Here, an example of processing performed by the response availability determination unit 11b will be described with reference to FIG. For example, if the reliability available for response is only 1, the response availability determination unit 11b extracts only cache data with reliability 1 and notifies the response processing unit 11a.

  In the first embodiment, the response availability determination unit 11b is described as a processing unit different from the response processing unit 11a. However, the response processing unit 11a including the response availability determination unit 11b may be configured. Further, the response availability determination unit 11b is configured as a processing unit that determines availability according to the purpose of use, and each process that handles the cache data 12a, such as the response processing unit 11a, the recursive query processing unit 11c, and the data registration processing unit 11d. The unit may use the determination result of availability.

  The recursive query processing unit 11c, when requested by the response processing unit 11a to query the DNS server apparatus 120, uses the address of the DNS server apparatus 120 included in the cache data 12a to recursively perform the DNS server apparatus 120. It is a processing unit that performs an inquiry process. The recursive query processing unit 11c is also a processing unit that performs processing for passing a response received from the DNS server device 120 to the data registration processing unit 11d.

  The data registration processing unit 11d is a processing unit that performs processing for registering the response from the DNS server apparatus 120 passed from the recursive query processing unit 11c as cache data 12a after associating it with “reliability”. Here, a configuration example of the cache data 12a and a setting example of “reliability” will be described with reference to FIGS.

  FIG. 3 is a diagram illustrating a configuration example of the cache data 12a. As shown at 31 in the figure, the cache data 12a is composed of n RRsets (resource record sets). Each RRset includes the items shown in 32 of FIG. The RRset is a group of resource records having the same “NAME”, “TYPE”, and “CLASS” as a single group. Each RRset includes an item of “reliability”, which is an item set by the data registration processing unit 11d described above. Next, an example of setting the reliability will be described with reference to FIG.

  FIG. 4 is a diagram illustrating a setting example of reliability. The “reliability” set by the data registration processing unit 11d for the response type from the DNS server device 120 shown in 42 of FIG. Here, what is shown in FIG. 42 is a description in Chapter 5.4 of RFC2181. RFC (Request For Comment) is a document formally issued by the Internet Engineering Task Force (IETF), an organization that establishes technical standards related to the Internet, and RFC2181 summarizes the specifications for DNS.

  As shown in 42 of FIG. 4, in the description of RFC2181, section 5.4, “data classification” indicating the classification of response data for recursive queries, “detailed information” which is detailed information about the classification of each data "Respondence to client" is used to indicate whether the response can be used for a response to the DNS client device, and the reliability of the response is roughly classified into seven types from high reliability to low reliability. is doing.

  Note that “A” to “G” described in the item of “reliability” are given for convenience of explanation, and “A” indicates the rank with the highest reliability. In addition, in the description of RFC 2181 in section 5.4, it is stipulated that the response of reliability “G” must not be used for the response to the DNS client device as to whether or not the response to the client is possible. There is no set rank.

  Next, a setting example of “reliability” will be described. An example of “reliability” set by the data registration processing unit 11d is shown at 41 in FIG. First, reliability A, B, and E shown in 42 of FIG. 14 are excluded because they are not responses that are generally used as cache data. The reliability is C data (the authoritative query response included in the Answer part (AA bit ON)), the reliability is “1”, and the reliability is D data (the authority part is included in the Authority part). For the query response (AA bit ON)), the reliability is determined as “2”.

  41 shows the case where the “reliability” is determined in a one-to-one correspondence with the “reliability” shown in FIG. 42, but the present invention is not limited to this. ”May correspond to one“ reliability ”. Further, one “reliability” may be associated with a plurality of “reliabilities”.

  FIG. 4 shows an example in which “reliability” and “reliability” shown in 42 of FIG. 4 are associated with each other. However, “reliability” may be set according to the use purpose of the cache data. Good. For example, data to be registered for cache data has a reliability of 1 to 3, data that can be used for recursive queries to the DNS server apparatus has a reliability of 1 to 2, and data that can be used for a response to the DNS client apparatus has a reliability of 1 Thus, the reliability can be determined.

  Returning to the description of FIG. 2, the storage unit 12 will be described. The storage unit 12 is a storage unit configured by a storage device such as a nonvolatile RAM (Random Access Memory) or a hard disk device, and stores cache data 12a. The cache data 12a is data having the configuration already described with reference to FIG. 3, and includes the “reliability” set by the data registration processing unit 11d. The cache data 12a is used for a response to the DNS client device 110 or a recursive query to the DNS server device 120. The cache data 12a can be used for statistics and analysis by performing a memory dump or the like.

  The communication processing unit 13 is a communication device that performs data transmission / reception with the DNS client device 110 and the DNS server device 120, and includes a communication interface board such as a LAN (Local Area Network) board.

  Next, a processing procedure when the cache server device 10 according to the first embodiment makes a response to the DNS client device 110 will be described with reference to FIG. FIG. 5 is a flowchart of the response process according to the first embodiment. As shown in the figure, when the cache server device 10 receives a request message (query request) (step S101), it is determined whether or not there is cache data 12a including an answer to the request message (step S102). If the corresponding cache data 12a exists (step S102, Yes), it is then determined whether or not the reliability of the cache data 12a determined to be applicable in step S102 is greater than or equal to the response threshold ( Step S103).

  If the reliability is equal to or higher than the response threshold (step S103, Yes), a response is sent to the DNS client device 110 using the cache data (step S104), and the process is terminated.

  On the other hand, if it is determined in step S102 that there is no corresponding cache data (step S102, No), or if it is determined in step S103 that the reliability is less than the response threshold (step S103, No). Then, a recursive query process for the DNS server device 120 is executed (step S105). The detailed processing contents of this recursive inquiry processing (step S105) will be described later with reference to FIG.

  The cache server device 10 that has executed the recursive query process (step S105) responds to the DNS client device 110 using the recursive query result (name resolution result) (step S106). Further, the cache server device 10 executes a process of registering the inquiry result as the cache data 12a (step S107) and ends the process.

  Next, detailed processing contents of the cache data registration processing (step S107) shown in FIG. 5 will be described with reference to FIGS. FIG. 6 shows only the most basic processing procedure, and FIG. 7 shows a detailed processing procedure including a registration permission determination process using a registration threshold value and a cache data update process.

  FIG. 6 is a flowchart of the process procedure of the cache data registration process according to the first embodiment. As shown in the figure, when the data registration processing unit 11d receives a resource record via the recursive query processing unit 11c (step S201), the reliability is set according to a predetermined setting criterion (for example, see FIG. 4). (Step S202). And the resource record linked | related with the reliability is registered into the memory | storage part 12 as the cache data 12a. In association with the reliability, the cache data 12a itself may include the reliability as shown in FIG. 3, or may be linked to the reliability. Further, the cache data 12a itself may be associated with the reliability and the cache data 12a by storing the cache data in a cache area classified according to the reliability without including the reliability.

  Next, a case where a registration availability determination process using a registration threshold and a cache data update process are added to the processing procedure shown in FIG. 6 will be described with reference to FIG. FIG. 7 is a flowchart showing a modification of the processing procedure shown in FIG. As shown in the figure, when the data registration processing unit 11d receives a resource record via the recursive query processing unit 11c (step S301), the reliability is set according to a predetermined setting criterion (for example, see FIG. 4). (Step S302). Subsequently, it is determined whether or not the reliability is equal to or higher than a predetermined registration threshold (step S303). If the reliability is equal to or higher than the registration threshold (step S303, Yes), is this resource record already registered? It is determined whether or not (step S304).

  If the result of determination in step S304 is that a resource record has already been registered (step S304, Yes), whether or not the reliability is different between the already registered resource record and the resource record received in step S301. Determination is made (step S305). If the reliability is different (step S305, Yes), the corresponding cache data 12a is updated (step S307), and the process is terminated.

  Although FIG. 7 shows the case where the cache data 12a corresponding to the case where the reliability is different is shown, the present invention is not limited to this, and the reliability of the new resource record is more than the reliability of the already registered resource record. The cache data 12a may be updated only when it is higher.

  Subsequently, a case where the determination condition is not satisfied in steps S303 to S305 will be described. If it is determined in step S303 that the reliability is less than the registration threshold (No in step S303), or if it is determined in step S305 that the reliability matches (step S305, No), the resource record is stored. Discard (step S308) and end the process without updating the cache data 12a.

  If it is determined in step S304 that the corresponding resource record has not been registered yet (step S304, No), the resource record associated with the reliability is newly registered as cache data 12a (step S306). Exit.

Next, detailed processing contents of the recursive inquiry processing (step S105) shown in FIG. 5 will be described with reference to FIG. FIG. 8 is a flowchart of the process procedure of the recursive query process according to the first embodiment. As shown in the figure, the recursive query processing unit 11c instructed by the response processing unit 11a to perform the recursive query to the DNS server device 120 determines whether or not there is the corresponding cache data 12a, that is, the query destination DNS. It is determined whether there is an NS record and a blue record (A record or AAAA record) indicating the server apparatus 120 (step S401).

  If the corresponding cache data 12a exists (step S401, Yes), the inquiry destination is shortcut by using the DNS server apparatus 120 indicated in the cache data 12a as the inquiry destination (step S402). On the other hand, when there is no corresponding cache data 12a (step S401, No), the inquiry destination is the DNS server of the root zone.

  Subsequently, the recursive inquiry processing unit 11c executes an inquiry to the DNS server apparatus 120 determined in step S402 or step S403 (step S404), and an inquiry result (formal answer or delegation) from the DNS server apparatus 120. If (answer) is received (step S405), it is determined whether the inquiry result is an official answer (step S406). If the inquiry result is an official answer (step S406, Yes), the process is terminated. On the other hand, when the inquiry result is a delegation answer (No at step S406), the inquiry destination is the DNS server device 120 of the lower zone (lower hierarchy) (step S407), and the processing procedure after step S404 is repeated. Become.

  8 shows a general processing procedure of the recursive query, but when performing a recursive query process for the DNS server device 120, the query destination DNS server device is performed each time the recursive query is performed. A SLIST that is a list of 120 is generated. Then, the resource record included in the cache data 12a determined as Yes in step S401 is added to the SLIST, and then the query in step S404 is executed.

  Next, the effect of the recursive query process shown in FIG. 8 will be described with reference to FIGS. FIG. 9 is a diagram for explaining the effect of the recursive query processing according to the first embodiment, and FIG. 16 is a diagram illustrating an outline of the recursive query processing according to the related art.

  First, recursive query processing according to the prior art will be described with reference to FIG. As shown in FIG. 16, the DNS server device α, jp. DNS server device β, co. jp. If there is a DNS server device γ that manages the zone, org. co. jp. The conventional cache server device that is requested to resolve the name of org. co. jp. (See (1) of FIG. 16).

  If the response from the DNS server device α is a delegation response (see (1) ′ in FIG. 16), the DNS server device β is informed by using information indicating the DNS server device β included in the delegation response. Org. co. jp. (See (2) in FIG. 16), and if the answer from the DNS server device β is a delegated answer (see (2) ′ in FIG. 16), the DNS server device γ included in the delegated answer To the DNS server γ by using the information indicating the org. co. jp. (See (3) of FIG. 16). If the answer from the DNS server device γ is an official answer (see (3) ′ in FIG. 16), the recursive query process is terminated.

  Thus, in the recursive query processing according to the prior art, it is necessary to repeat the query recursively until the DNS server device that returns the official answer is reached, starting from the DNS server device of the upper layer.

  Next, recursive inquiry processing according to the first embodiment will be described with reference to FIG. 9 are the same as those in FIG. 16, there are three DNS server devices DNS server devices α to γ, and the cache server device 10 is org. co. jp. It is assumed that name resolution is requested.

  Incidentally, in 91 of FIG. co. jp. As for the inquiry processing when the name resolution is requested, in org. 92 in FIG. co. jp. Each case is shown when name resolution is requested.

  First, the cache server device 10 according to the first embodiment is configured as co. jp. Org. Which is a domain belonging to the zone. co. jp. Is requested (see 91 in FIG. 9), each delegation answer is cached as cache data 12a. Therefore, co. jp. New. Which is a domain belonging to the zone. co. jp. Can be directly inquired to the DNS server device γ by referring to the cache data 12a (see (4) in 92 of FIG. 9). Further, even when a direct inquiry to the DNS server device γ cannot be made due to reasons such as TTL (Time To Live) expired, the closest authority server (for example, the DNS server device β) is selected. A recursive query can be made from the starting point.

  As described above, the cache server device 10 according to the first embodiment registers the delegation response received from the DNS server device in the storage unit 12 after associating it with the reliability. By using the data 12a for the recursive query, the number of queries in the recursive query can be reduced, and the reliability of the query can be ensured.

  As described above, in the first embodiment, the response from the DNS server apparatus received by the data registration processing unit via the recursive query processing unit is associated with the newly introduced concept “reliability”. In the scene where the registered cache data is used, the response availability determination unit determines that cache data that is equal to or greater than a predetermined response threshold value can be responded, and the response processing unit Since the cache data determined to be responsive can be used for response processing, a wide range of usable cache data can be registered, and a wide range of cache data can be used efficiently.

  In the first embodiment described above, a response having a reliability equal to or higher than the registration threshold is registered as cache data, and cache data having a reliability equal to or higher than the response threshold is used for response processing, and the registered cache is used. The case where data is used for recursive query processing, that is, the case where all cache data having reliability equal to or higher than the registration threshold is used for recursive query processing has been shown. However, not limited to this, it is assumed that a threshold value for inquiry is used in the recursive query process, and only cache data whose reliability is equal to or higher than the threshold value for inquiry is used for the recursive query process. Also good. In this way, the reliability of the recursive query can be flexibly changed.

  In the first embodiment, the case where the response availability determination unit determines whether the cache data can be used for the response processing using the response threshold value has been described. However, the response processing unit includes the response availability determination unit. It may be configured. In addition, a determination processing unit that determines whether or not cache data can be used for processing using each threshold such as a registration threshold, a response threshold, and an inquiry threshold (registration processing, response processing, inquiry processing, etc.) is configured. Also good. In this way, even when a usage process such as a statistical / analytical threshold is added, it is possible to easily add or manage a threshold according to the usage purpose of the cache data.

  Moreover, it is good also as comprising so that each said threshold value may be a value which a maintenance person can change, and changing each threshold value according to an operation state. In this way, the reliability of each process such as the registration process, the response process, and the inquiry process can be flexibly changed according to the operation policy of the cache server device. Each threshold value can be changed by, for example, reading a setting file when the server process is activated. Alternatively, the setting file may be read during the operation of the server process.

  In the first embodiment, the case where the reliability is multi-valued data (for example, see FIG. 4) has been described. However, the reliability may be a binary flag. Therefore, the case where the reliability is a binary flag will be described below with reference to FIG. FIG. 10 is a diagram illustrating a modification of the cache server device according to the first embodiment.

  As shown in FIG. 10, the cache server device 10a according to the modified example takes two values of “response possible” and “response impossible” as the reliability. For example, “1” in a 1-bit area may be “response possible”, and “0” may be “response impossible”. As described above, since the reliability is set to a binary flag, the reliability reference process in the cache data registration process and the cache data use process (response process to the DNS client device) can be simplified. Efficiency can be increased.

  In the second embodiment, a cache server apparatus having a cache area corresponding to the reliability of answers will be described. FIG. 11 is a diagram illustrating an overview and features of the cache server device 10b according to the second embodiment. As shown in the figure, the cache server device 10b includes two cache areas, a response cache area and a recursive query cache area. In the cache data registration process, the response received from the DNS server device 120 via the recursive query function is distributed and registered in each of these cache areas (see (3) in FIG. 11).

  The cache data registered in the response cache area is used when the response function performs a response process (see (1) in FIG. 11), and the cache data registered in the recursive query cache area is recursively. It is used when the inquiry function performs inquiry processing (see (2) in FIG. 11).

  As described above, in the cache server device 10b according to the second embodiment, a plurality of cache areas corresponding to the reliability are provided. That is, unlike the first embodiment in which the reliability is set for the cache data itself, in the second embodiment, the cache area for storing the cache data is associated with the reliability. By doing so, it is possible to simplify the processing when using the cache data.

  Of the cache data of each cache area shown in the figure, “A” and “B” are registered in both cache areas. Such data synchronization processing is performed by the cache data registration processing shown in FIG. For example, the reliability 1 cache data is “A” and “B”, the reliability 2 cache data is “C” and “D”, and the reliability can be used as a response to the DNS client device 110. The case where is only 1 will be described.

  In such a case, in the cache data registration process, the cache data with reliability 1 is registered in the response cache area, and the cache data with reliability 1 and 2 are registered in the recursive query cache area. For example, in the cache data registration process, the cache data A is registered in both cache areas, but the cache data C is registered only in the recursive query cache area.

  Next, the configuration of the cache server device 10b according to the second embodiment will be described with reference to FIG. FIG. 12 is a block diagram illustrating the configuration of the cache server device 10b according to the second embodiment. In the figure, only processing units necessary for explaining the features of the cache server device 10b are shown, and a processor such as a CPU (Central Processing Unit) and a process that functions as a general cache server are shown. About the point which abbreviate | omits description about a part, it is the same as that of FIG. Hereinafter, differences from the first embodiment will be described, and description of common points will be omitted.

  As shown in FIG. 12, the cache server device 10b includes a response cache area 12b and a recursive query cache area 12c in the storage unit 12. Each cache area stores the cache data distributed by the data registration processing unit 11d. As a format of the cache data stored in each cache area, for example, a hash table can be used for both cache areas. Thus, the processing efficiency when using cache data can be improved by making the cache data stored in each cache area into the same format.

  The data registration processing unit 11d sets “reliability” for the response from the DNS server device 110 passed from the recursive query processing unit 11c, and sends a response from the DNS server device 120 to the cache area corresponding to each reliability. Is a processing unit that performs processing for storing. For example, the data registration processing unit 11d stores only responses with reliability 1 in the response cache area 12b, and stores responses with other reliability levels including reliability 1 in the recursive query cache area 12c. .

  The cache server device 10b shown in FIG. 12 does not include the response availability determination unit 11b, unlike the cache server device 10 (see FIG. 2) shown in the first embodiment. The reason is that the data registration processing unit 11d distributes and stores the cache data in the cache area corresponding to each usage purpose such as the response cache area 12b and the recursive query cache area 12c. This is because all the cache data stored in the cache area 12c may be used.

  Next, a processing procedure when the cache server device 10b according to the second embodiment makes a response to the DNS client device 110 will be described with reference to FIG. FIG. 13 is a flowchart of the response process according to the second embodiment. As shown in the figure, when the cache server device 10b receives a request message (query request) (step S501), it is determined whether there is cache data corresponding to the response cache area 12b (step S502). If there is corresponding cache data (step S502, Yes), a response is sent to the DNS client device 110 using the cache data (step S503), and the process is terminated.

  On the other hand, when it is determined in step S502 that there is no corresponding cache data (No in step S502), a recursive query process for the DNS server device 120 is executed (step S504). The detailed processing contents of this recursive inquiry processing (step S504) are the same as those in FIG.

  The cache server apparatus 10b that has executed the recursive query process (step S504) responds to the DNS client apparatus 110 using the recursive query result (name resolution result) (step S505). Further, the cache server device 10b executes a process of registering the inquiry result as cache data (step S506), and ends the process.

  Next, detailed processing contents of the cache data registration processing (step S506) shown in FIG. 13 will be described with reference to FIG. FIG. 14 is a flowchart illustrating a processing procedure of cache data registration processing according to the second embodiment. As shown in the figure, when the data registration processing unit 11d receives a resource record via the recursive query processing unit 11c (step S601), the reliability is set according to a predetermined setting criterion (for example, see FIG. 4). (Step S602). Subsequently, it is determined whether or not the reliability is greater than or equal to a predetermined registration threshold (step S603). If the reliability is greater than or equal to the registration threshold (step S603, Yes), the reliability of this resource record is for response. It is determined whether or not the threshold value is exceeded (step S604).

  If the result of determination in step S604 is that the reliability is greater than or equal to the response threshold (step S604, Yes), this resource record is stored in the response cache area 12b and the recursive query cache area 12c ( Step S605) The process ends. On the other hand, if the reliability is less than the response threshold (step S604, No), this resource record is stored in the recursive query cache area 12c (step S606), and the process is terminated. If it is determined in step S603 that the reliability is less than the registration threshold (step S603, No), the resource record is discarded (step S607), and the process is performed without storing in any cache area. finish. The data stored in the recursive query cache area in step S605 and step S606 is an NS record and a blue record (A record or AAAA record).

  As described above, in the second embodiment, a response cache area and a recursive query cache area are provided in the storage unit, and the data registration processing unit receives from the DNS server apparatus received via the recursive query processing unit. The response from the DNS server apparatus is stored in both the response cache area and the recursive query cache area, or only in the response cache area based on the determined reliability. Configured. Therefore, the registered cache data can be searched efficiently.

  In the second embodiment, the case where the response cache area and the recursive query cache area are provided in the storage unit has been described. However, the present invention is not limited to this, and a cache area may be provided for each reliability level. A cache area may be provided for each group of reliability.

  Further, as described above, all the cache data stored in each cache area can be a hash table, but the search algorithm when the response processing unit refers to the response cache area, and the recursive query processing unit The search algorithm for referring to the recursive query cache area may be different from the search algorithm.

  For example, as a search algorithm used by the response processing unit, a general calculation algorithm that collectively performs a hash conversion of domain names (for example, aaa.co.jp.) is used. On the other hand, as a search algorithm used by the recursive query processing unit, a hash value for each label (“aaa”, “co”, “jp”) of a domain name (for example, aaa.co.jp.) is used from the right label. It is assumed that a search algorithm for determining a match of domain names while storing in the direction of the left label is used.

  In this way, the processing efficiency when using cache data can be improved by switching the search algorithm when using cache data according to the purpose of use. Such a search algorithm may be configured to be included in each use unit such as a response processing unit and a recursive query processing unit, or search algorithm switching for managing a plurality of search algorithms and switching each search algorithm. The units may be configured as independent processing units.

  In each of the above-described embodiments, each device that implements the present invention has been described in terms of functions. However, each function of each device can also be realized by causing a computer such as a personal computer or a workstation to execute a program. .

  In other words, the various processing procedures described above can be realized by executing a program prepared in advance on a computer. These programs can be distributed via a network such as the Internet. Further, these programs can be recorded on a computer-readable recording medium such as a hard disk, a flexible disk (FD), a CD-ROM, an MO, and a DVD, and can be executed by being read from the recording medium by the computer.

  As described above, the cache server device, the cache control method, and the cache server device program according to the present invention are useful for improving the performance of the cache server device, and particularly for reducing the processing time of recursive query processing for the DNS server device. Is suitable.

1 is a diagram illustrating an overview and characteristics of a cache server device according to Embodiment 1. FIG. 1 is a block diagram illustrating a configuration of a cache server device according to Embodiment 1. FIG. It is a figure which shows the structural example of cache data. It is a figure which shows the example of a setting of reliability. 6 is a flowchart illustrating a processing procedure of response processing according to the first embodiment. 7 is a flowchart illustrating a processing procedure of cache data registration processing according to the first embodiment. It is a flowchart which shows the modification of the process sequence shown in FIG. 6 is a flowchart illustrating a processing procedure of recursive inquiry processing according to the first embodiment. It is a figure explaining the effect of the recursive inquiry process which concerns on Example 1. FIG. It is a figure which shows the modification of the cache server apparatus which concerns on Example 1. FIG. It is a figure which shows the outline | summary and the characteristic of the cache server apparatus based on Example 2. FIG. FIG. 6 is a block diagram illustrating a configuration of a cache server device according to a second embodiment. 12 is a flowchart illustrating a processing procedure of response processing according to the second embodiment. 10 is a flowchart illustrating a processing procedure of cache data registration processing according to the second embodiment. It is a figure which shows the outline | summary of the cache server apparatus based on a prior art. It is a figure which shows the outline | summary of the recursive inquiry process which concerns on a prior art.

Explanation of symbols

10, 10a, 10b Cache server device 11 Control unit 11a Response processing unit 11b Response availability determination unit 11c Recursive query processing unit 11d Data registration processing unit 12 Storage unit 12a Cache data 12b Response cache area 12c Recursive query cache area 13 Communication processing unit 110 DNS client device 120 DNS server device

Claims (9)

Inquiry responses to the DNS server device are accumulated as cache data, and when a DNS query request is received from the DNS client device, an immediate response to the DNS client device or recursion to the DNS server device based on the cache data A cache server device that returns one of the responses after making a basic inquiry,
A registration means for registering the response of the inquiry to the DNS server device as the cache data after associating the response with the reliability of the response;
A cache server device, comprising: availability determination means for determining availability of the cache data registered by the registration means based on the reliability. Response means for making an immediate response to the DNS client device based on the determination result of the availability determination means;
The availability determination unit includes:
2. The cache data whose reliability is equal to or higher than a response threshold is determined to be usable for an immediate response before the response means performs an immediate response to the DNS client device. The cache server device described. The registration means includes
3. A registration threshold having a value lower than the response threshold is used, and the inquiry response having the reliability equal to or higher than the registration threshold is registered as the cache data. The cache server device according to 1. Further comprising inquiry means for making a recursive inquiry to the DNS server device based on the determination result of the availability determination means;
The availability determination unit includes:
Using an inquiry threshold having a value lower than the response threshold,
Before the inquiry means makes a recursive inquiry to the DNS server device, it is determined that the cache data whose reliability is equal to or higher than the inquiry threshold can be used for the recursive inquiry. The cache server device according to claim 2, wherein: Further comprising cache data storage means having a cache area partitioned based on the reliability,
The registration means includes
The cache server device according to any one of claims 1 to 4, wherein an inquiry response to the DNS server device is registered in each cache area corresponding to the reliability. The data structure of the cache data registered by the registration means is a hash table,
6. The cache server device according to claim 1, further comprising search algorithm switching means for switching a search algorithm for searching the cache data for each use purpose of the cache data. The registration means includes
The cache data is updated by using a new response when the reliability of the inquiry response to the DNS server apparatus is different from the reliability of the cache data already registered. 6. The cache server device according to any one of 6. Inquiry responses to the DNS server device are accumulated as cache data, and when a DNS query request is received from the DNS client device, an immediate response to the DNS client device or recursion to the DNS server device based on the cache data Control method that returns one of the responses after making a basic query,
A registration step of registering as a cache data after associating an inquiry response to the DNS server device with the reliability of the response;
A cache control method comprising: a cache availability method for determining whether or not the cache data registered in the registration process is usable based on the reliability. Inquiry responses to the DNS server device are accumulated as cache data, and when a DNS query request is received from the DNS client device, an immediate response to the DNS client device or recursion to the DNS server device based on the cache data A cache server device program that returns one of the responses after making a basic inquiry,
A registration procedure for registering as a cache data after associating an inquiry response to the DNS server device with the reliability of the response;
A program for a cache server device, which causes a computer to execute an availability determination procedure for determining availability of the cache data registered by the registration procedure based on the reliability.

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