JP2010074596A - Active dns device and name solution processing method thereof and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve reliability of a computer system that attains load distribution of hosts by managing a plurality of hosts (computer devices) with one host name physically. <P>SOLUTION: In a DNS server 101 that performs name solution processing to a plurality of servers 111, 112 on which IP address management is performed with the same host name by a DNS, a supervisory processing section 106 supervises working states of the servers 111, 112 registered and managed by a DNS definition file 109. In a case where it is detected that the server 111 stops, the registration information of the server 111 is deleted or changed by a DNS setting switching section 105, thereby preventing an external terminal 113 from reading presence of the stopped server 111. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a DNS (Domain Name System) technique for performing name resolution processing of each communication terminal (computer device) in an IP network environment such as the Internet or an intranet, and in particular, a plurality of hosts (computer devices) that are physically present. The present invention relates to a technique suitable for efficiently performing name resolution in a system that is virtually used as a single host.

  Conventionally, when performing name resolution of each communication terminal (computer device) in an IP network environment, as a technique for virtually using a plurality of hosts (computer devices) as one host, for example, Patent Literature There is a technique described in 1.

  This technology can guide a client (computer device) to an optimal server in terms of network topology, cost, network capacity, etc. when there are multiple servers (computer devices, hosts) for one domain name. It is to make.

  Specifically, in the address resolution by the DNS server, the DNS server has a correspondence table of the inquiry source IP network address and the inquiry source group number, and also has a correspondence table of the domain name, the inquiry source group number, and the response IP address. In response to an address inquiry from a resolver (client side program that notifies the name server of the host name and requests an IP address search, or vice versa), these tables are searched for the IP address. Respond.

  In this way, load distribution to the system and connection from the client to the optimum server can be achieved, and maintenance of these tables can be facilitated.

  A similar technique is DNS round robin. This technique prevents a concentration of access to one computer by assigning a plurality of IP addresses to one domain name and answering in turn each time an inquiry is made.

  In Patent Document 2, in an IP network, access to a high-load Web server is efficiently regulated, the total throughput is improved, the Web server and the system are prevented from being stopped, and at the same time, the service efficiency to the user is improved. A technique for realizing the improvement is described.

  Specifically, in the congestion control apparatus installed in the IP network, the correspondence between the IP address and the host name is stored, and when a new request is made from the client to the Web server, the DNS server When an IP address is acquired and it is determined that the Web server of the IP address is in a congestion state, a different IP address that is not in a congestion state is searched for the same host name in the stored correspondence relationship, and the IP address The request from the client is distributed to the Web server at the address.

  In general, a DNS server statically holds information for converting a host name into an IP address. Therefore, when performing name resolution, consider whether or not the host is actually running. Without converting to IP address.

  In this case, there is a possibility that the client tries to connect to the client by resolving the name of the host that is not running.

  In the technique of Patent Document 2, even when congestion occurs in hosts with a plurality of IP addresses managed by the same host name, the information on the congested host remains as it is. In response to this, the IP address of the congested host is also read out, accessed to the host, and it is known from the outside that a congestion state has occurred in the host. There is a risk that the system itself consisting of the computer apparatus may be judged as “many troubles” or “unreliable”.

JP 2003-115862 A JP 2006-222631 A

  The problem to be solved is that in the conventional technique, whether the connection destination is in the normal operation state or the degenerate operation state is known from the outside by the DNS name resolution processing.

  The object of the present invention is to solve these problems of the prior art and to improve the reliability of a computer system that physically manages a plurality of hosts (computer devices) with one host name and distributes the load of each host. It is.

  In order to achieve the above object, in the present invention, in a computer device (DNS server) that performs name resolution processing by DNS, the operating state of each registered and managed host is monitored, and the monitoring target host is stopped. When detected, the registration information of the host is deleted or changed.

  According to the present invention, the IP address of the host in which the failure has occurred is not answered in response to the name resolution query from the external terminal, so that the external terminal does not cause a phenomenon of trying to connect to the stopped host. Even if the external terminal refers to the name resolution answer, the presence of the stopped host is not read. For example, a system comprising a plurality of hosts read by DNS round robin It can be avoided that the reliability is impaired.

  The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1A is a block diagram showing a first configuration example of an active DNS apparatus according to the present invention, FIG. 1B is a block diagram showing a second configuration example of an active DNS apparatus according to the present invention, and FIG. FIG. 3 is a flowchart showing a first processing operation example of the name resolution processing method of the active DNS apparatus according to the present invention; FIG. 3 is a flowchart showing a second processing operation example of the name resolution processing method of the active DNS apparatus according to the present invention; FIG. 4 is a flowchart showing a third processing operation example of the name resolution processing method of the active DNS apparatus according to the present invention, FIG. 5 is an explanatory diagram showing a configuration example of the timeout number file in FIG. 1, and FIG. FIG. 7 is an explanatory diagram showing a configuration example of the DNS definition file in FIG. 1.

  1A and 1B, reference numeral 101 denotes an active DNS server as an active DNS apparatus according to the present invention. This active DNS server 101 is the same as the monitoring target server (1) 111, the monitoring target server (2) 112, and the terminal 113. In addition, a computer configuration including a CPU (Central Processing Unit), a main memory, a display device, an input device, and an external storage device, and programs and data recorded on a storage medium such as a CD-ROM via an optical disk drive device, etc. After installation in the external storage device, the function of each processing unit is executed by reading from the external storage device into the main memory and processing by the CPU.

  That is, the active DNS server 101 includes active DNS systems 102 and 103 and a DNS process 110 as functions to execute computer processing by being programmed. Further, the active DNS systems 102 and 103 are shown in the active DNS system 103. In addition, the system control unit 104, the DNS setting switching processing unit 105, and the monitoring processing unit 106 are provided, and information such as the timeout count file 107, the status file 108, and the DNS definition file 109 is stored in a storage device (not shown). ing.

  As shown in the item description 501 and the data example 502 in FIG. 5, the timeout number file 107 is set with the number of timeouts as the item name, and the ping timeout number (0 to 3) is set as the value (content description) for the item. be registered.

  In the status file 108, as shown in the item description 601 and the data example 602 in FIG. 6, the status is set as the item name, and the monitoring target operating state (Normal: normal, Error: Abnormal) is registered.

  In the DNS definition file 109, as shown in the item description 701 and the data example 702 in FIG. 7, the host name and IP address are set as the item name, and the target host name is set as the value (content description) for the item. (HostA) and the IP address of the target host are registered.

  FIG. 1A shows a normal configuration of the active DNS server 101, and FIG. 1B shows a configuration of the active DNS server 101 when a failure occurs in the monitoring target.

  The active DNS systems 102 and 103 included in the DNS server 101 are activated by the number of monitoring target servers (1) 111 and monitoring target servers (2) 112, which are monitoring target hosts, and each specific monitoring target server (1). 111, the monitoring target server (2) 112 may be monitored. However, as shown in FIG. 1B, in the active DNS system 103, the monitoring target server (1) 111 and the monitoring target server (2) 112 are A description will be given of a configuration for performing monitoring.

  That is, in the configuration of FIG. 1A, two active DNS systems 102 and 103 are activated, one active DNS system 102 monitors the monitoring target server (1) 111, and the other active DNS system 103 Although the monitoring target server (1) 112 is monitored, in the configuration of FIG. 1B, the active DNS system 103 monitors the monitoring target server (1) 111 and the monitoring target server (2) 112.

  In the active DNS system 103, the system control unit 104 performs overall control, the monitoring processing unit 106 monitors the monitoring target servers (1) 111 and (2) 112, and the DNS setting switching processing unit 105 performs monitoring. When the stop of the target servers (1) 111 and (2) 112 is detected, the host definition managed by the DNS definition file 109 is changed.

  The DNS definition file 109 stores the IP addresses of the monitoring target servers (1) 111 and (2) 112 in association with the same host name, and the monitoring processing unit 106 monitors the monitoring target servers (1) 111, ( 2) The operation state of 112 is monitored, and when the stop state of the monitored server (1) 111 is detected, the detection result is stored in the status file 108.

  The DNS setting switching processing unit 105 reads the detection result by the monitoring processing unit 106 stored in the status file 108, and if the monitoring target server (1) 111 is in a stopped state, the IP address of the monitoring target server (1) 111 Are deleted from the DNS definition file 109.

  Alternatively, the DNS setting switching processing unit 105 reads the detection result by the monitoring processing unit 106 stored in the status file 108, and is registered in the DNS definition file 109 if the monitoring target server (1) 111 is in a stopped state. The IP address of the monitored server (1) 111 is changed.

  The DNS process 110 refers to the information stored in the DNS definition file 109 in response to the inquiry of the IP address of the monitoring target server designated by the host name from the external terminal 113 connected via the network, and One of the IP addresses of the monitoring target servers (1) 111 and (2) 112 associated with the name is selected and returned.

  In the processing of the DNS process 110, if the information (IP address) regarding the monitoring target server (1) 111 is deleted from the information stored in the DNS definition file 109 by the DNS setting switching processing unit 105, the DNS process 110 Does not return the IP address of the monitoring target server (1) 111 to the external terminal 113, so there is no fear that the terminal 113 side accesses the monitoring target server (1) 111 in the operation stop state.

  Further, in the processing of the DNS process 110, if the information (IP address) regarding the monitoring target server (1) 111 is changed by the DNS setting switching processing unit 105 among the information stored in the DNS definition file 109, Since the DNS process 110 does not return the original IP address of the monitoring target server (1) 111 to the external terminal 113, there is no fear that the terminal 113 side accesses the original IP address destination.

  In this case, the DNS setting switching processing unit 105 generates table information in which the changed IP address is associated with the IP address of the monitoring target server (2) 112, for example, and stores the table information in the storage device. By referring to the information, the access addressed to the changed IP address from the terminal 113 can be addressed to the monitoring target server (2) 112.

  In particular, as the IP address changing process in the DNS setting switching processing unit 105, the original IP address of the monitoring target server (1) 111 in the stopped state is continuously stored in the DNS definition file 109 as it is. Further, by generating table information associated with the IP address of the monitored server (2) 112 and storing the original IP address in the storage device, for example, the IP that the DNS process 110 returns to the terminal 113 The IP address of the monitoring target server (1) 111 in the stopped state is included as the address.

  In this way, the original IP address of the monitoring target server (1) 111 in the stopped state is continued as it is stored in the DNS definition file 109, and the stopped state is used as the IP address that the DNS process 110 returns to the terminal 113. By including the IP address of the monitored server (1) 111, the terminal 113 can determine that the original IP address of the monitored server (1) 111 has not been deleted. (1) Even if 111 is in a substantially disconnected state, the degenerate operation state cannot be determined on the terminal 113 side even when compared with the normal time. As a result, it is possible to avoid a negative determination that the system itself has many troubles and low reliability.

  Note that the DNS process 110 selects an IP address to be returned to the terminal 113 in a round robin manner.

  In addition, the monitoring processing unit 106 stores the result of the monitoring processing in the timeout file 107, and when a failure is detected, registers information ("error") indicating the failure state in the status of the status file 108, and DNS The setting switching processing unit 105 is activated.

  Specifically, the monitoring processing unit 106 sends a ping command to each computer device of the monitoring target servers (1) 111 and (2) 112, counts the number of errors for each server, and the counted number of errors is If a predetermined threshold value is exceeded, it is detected that the server is in a stopped state.

  As described above, in this example, the DNS setting switching processing unit 105 edits the DNS definition file 109 so that the DNS process 110 does not return information on the monitoring target server that has failed in response to the inquiry from the terminal 113. To do.

  Hereinafter, the name resolution processing operation of the DNS server 101 according to the present invention will be described with reference to the flowcharts of FIGS.

  In FIG. 2, first, the presence or absence of the setting file 210 is confirmed (step S201). If the setting file 210 exists, a variable value is acquired from the setting file 210 (step S202), and the acquired value is checked (step S203). ), Initialization processing is performed (step S204), and the monitoring processing unit 205 is called.

  When the process of the monitoring processing unit 205 is completed, a variable value is acquired from the status file 211 (step S206), the acquired variable is checked (step S207), and if the variable value is “error”, the monitoring target Is not “error”, it is determined whether 10 seconds have passed without notifying that the monitoring target is stopped (step S209). If the second has elapsed, the monitoring processing unit 205 is called again, and after the processing is completed, the processing of steps S206 to S209 is repeated.

  FIG. 3 shows the PING issue processing operation of the monitoring processing unit 106. The monitoring processing unit 106 first acquires a variable value from the setting file 318 (step S301), and checks the acquired variable (step S302). ).

  Next, it is confirmed whether or not the timeout number file 319 exists (step S303). If the timeout number file 319 does not exist, the timeout number file 319 is created and set to a value “0” (step S304). If the file exists, the process proceeds to the next step S305.

  In the next process, the presence / absence of the status file 320 is confirmed (step S305). If the status file 320 does not exist, a status file is created and a value “Error” is set (step S306). If so, the process proceeds to the next step S307.

  In step S307, the status file value is checked. If the value is other than "Normal", the timeout count is stored in the timeout count file 319 (step S315), and the process is terminated.

  If “Normal”, PING is issued (step S308). It is determined whether or not the value of the execution result of this PING is “0” (step S309). If it is not “0”, the timeout count value is confirmed (step S310), and the timeout count is less than 3 In this case, a value obtained by adding “1” to the timeout count is set (step S311), the timeout count value is checked again (step S312), and if the timeout count value is “3”, the status file 320 is stored. The value “Error” is set (step S313), the DNS setting switching process is called (step S314), and the timeout number value is stored in the timeout number file 319 (step S315).

  When the value of the status file 320 is “Normal”, a PING is issued (step S308). When the result value is other than “0”, it is determined whether or not the number of times of timeout is “less than 3”. Confirm (step S316), if it is “3 or more”, do nothing, and if it is “less than 3”, add “1” to the timeout count (step S317) and save the timeout count in the timeout count file 319. (Step S315) The process ends.

  FIG. 4 shows the processing operation of the DNS setting switching processing unit 105. The DNS setting switching processing unit 105 first acquires a variable value from the setting file 405 (step S401) and checks the acquired variable ( Step S402), the DNS setting file is changed (Step S403), and the DNS server process is restarted (Step S404).

  As described above with reference to FIGS. 1A to 7, in this example, monitoring is performed in the DNS server 101 that executes name resolution processing for a plurality of servers 111 and 112 that are IP addresses managed by the DNS with the same host name. When the processing unit 106 monitors the operating states of the servers 111 and 112 registered and managed in the DNS definition file 109 and detects that the monitoring target server 111 has stopped, the DNS setting switching unit 105 The registration information of the server 111 is deleted or changed.

  By doing so, since the IP address of the server (111) in which the failure has occurred is not answered in response to the name resolution inquiry from the external terminal 113, the external terminal 113 is stopped by the server (111) ), And even if the external terminal 113 refers to the name resolution answer, the presence of the stopped server (111) is not read. For example, it can be avoided that the reliability of the system including a plurality of servers (111, 112) read by the DNS round robin is impaired.

  In addition, this invention is not limited to the example demonstrated using FIG. 1A-FIG. 7, It can change variously in the range which does not deviate from the summary. For example, although two servers are shown as monitoring target servers in this example, two or more servers may be monitored.

  The computer configuration of this example may be a computer configuration without a keyboard or optical disk drive. In this example, an optical disk is used as a recording medium. However, an FD (Flexible Disk) or the like may be used as a recording medium. As for the program installation, the program may be downloaded and installed via a network via a communication device.

It is a block diagram which shows the 1st structural example of the active DNS apparatus which concerns on this invention. It is a block diagram which shows the 2nd structural example of the active DNS apparatus which concerns on this invention. It is a flowchart which shows the 1st processing operation example of the name resolution processing method of the active DNS apparatus which concerns on this invention. It is a flowchart which shows the 2nd processing operation example of the name resolution processing method of the active DNS apparatus which concerns on this invention. It is a flowchart which shows the 3rd processing operation example of the name resolution processing method of the active DNS apparatus which concerns on this invention. It is explanatory drawing which shows the structural example of the timeout frequency file in FIG. It is explanatory drawing which shows the structural example of the status file in FIG. It is explanatory drawing which shows the structural example of the DNS definition file in FIG.

Explanation of symbols

  101: DNS server, 102, 103: Active DNS system, 104: System control unit, 105: DNS setting switching processing unit, 106: Monitoring processing unit, 107, 319: Timeout count file, 108, 211, 320: Status file 109: DNS definition file, 110: DNS process, 111: monitoring target server (1), 112: monitoring target server (2), 113: terminal, 210, 318, 405: setting file.

Claims (8)

A DNS device for performing name resolution of a plurality of computer devices having the same host name connected to an IP network by programmed computer processing,
As a means of performing programmed computer processing,
Definition file storage means for storing definition information in which the IP address of each computer device having the same host name is associated with the host name;
Monitoring processing means provided for each computer device for monitoring the operating state of the computer device and detecting the stopped state of the computer device;
Status file storage means for storing detection results by the monitoring processing means;
The detection result by the monitoring processing means stored in the status file storage means is read, and if there is a stopped computer device, the IP address of the computer device is deleted from the definition information stored in the definition file storage means DNS setting switching processing means to perform,
In response to the inquiry of the IP address of the computer device designated by the host name from the external terminal device, the definition information in the definition file storage means is referred to, and one of the IP addresses of the computer devices associated with the host name is selected. And an DNS process means for returning the active DNS apparatus. A DNS device for performing name resolution of a plurality of computer devices having the same host name connected to an IP network by programmed computer processing,
As a means of performing programmed computer processing,
Definition file storage means for storing definition information in which the IP address of each computer device having the same host name is associated with the host name;
Monitoring processing means provided for each computer device for monitoring the operating state of the computer device and detecting the stopped state of the computer device;
Status file storage means for storing detection results by the monitoring processing means;
The detection result by the monitoring processing means stored in the status file storage means is read, and if there is a stopped computer device, the IP address of the computer device in the definition information stored in the definition file storage means is changed. DNS setting switching processing means;
In response to the inquiry of the IP address of the computer device designated by the host name from the external terminal device, the definition information in the definition file storage means is referred to, and one of the IP addresses of the computer devices associated with the host name is selected. And an DNS process means for returning the active DNS apparatus. An active DNS device according to claim 2,
The DNS setting switching processing means
An active DNS device, wherein table information in which a changed IP address is associated with an IP address of another computer device having the same host name is generated and stored in a storage device. An active DNS device according to claim 2,
The DNS setting switching processing means
Table information in which the IP address of the computer device in the stopped state is associated with the IP address of another computer device having the same host name is generated and stored in the storage device.
The definition file storage means continuously stores the IP address of the computer in the stopped state,
An active DNS device, wherein the IP address returned by the DNS process means includes the IP address of the computer device in the stopped state. An active DNS device according to any one of claims 1 to 4,
The DNS process means includes:
An active DNS apparatus characterized in that selection of an IP address of a computer apparatus to be returned to the external terminal apparatus is performed in a round robin manner. An active DNS device according to any one of claims 1 to 5,
The monitoring processing means includes
A ping command is sent to each computer device, the number of errors for each computer device is counted, and if the counted number of errors exceeds a predetermined threshold, it is detected that the computer device is in a stopped state. Active DNS device. A DNS system name resolution processing method for performing name resolution of a plurality of computer devices having the same host name connected to an IP network by programmed computer processing,
A programmed computer processing procedure includes a processing procedure executed by each unit in the active DNS device according to any one of claims 1 to 6,
In accordance with the processing procedure of each means, the name resolution of the active DNS apparatus, wherein one IP address is selected and returned in response to the inquiry of the IP address of the computer apparatus designated by the host name from the external terminal apparatus Processing method.   The program for functioning a computer as each means in the active DNS apparatus in any one of Claims 1-6.

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