2.3.8 Operation in a DNS environment

You can use JP1/AJS in a DNS environment. To use JP1/AJS in a manager/agent configuration, define normal lookup on the DNS.

The following figure shows the settings required for name resolution by using normal lookup for JP1/AJS3 products.

Figure 2‒37: Settings required for name resolution by using normal lookup for JP1/AJS3 products

If you want to use a FQDN (Fully Qualified Domain Name) host name as the execution agent name for event jobs, you need to specify the settings described in this subsection. You do not need to specify these settings when using event jobs if there are no duplicated host names in the same network, in an environment that spans multiple domains, or if you do not plan to use event jobs.

When the settings described in this section are specified, each host obtains an FQDN host name from the local host name and sends it to the other hosts during communication between the manager and agent hosts when event jobs are executed. This allows the manager and agent hosts to uniquely identify each other and to correctly process the communication data.

You do not need to switch to using FQDN hosts names if all the host names in the same network are unique and no problems occur.

Organization of this subsection

(1) When to switch to using FQDN host names for event jobs
(2) Example of using FQDN host names when the DNS is used
(3) Notes on operation in a DNS environment

(1) When to switch to using FQDN host names for event jobs

You do not need to change the current settings if the event jobs use the DNS and host names that are unique in the same network. Follow the flowchart below to determine whether you need to switch to using FQDN host names for event jobs.

Figure 2‒38: Judging the necessity of switching to operation with host names in the FQDN format

New settings are required if the flowchart above indicates that you need to switch to using FQDN host names. For the setting procedure, see 6.3.5 Using fully qualified domain names (FQDN) when using event jobs during DNS operation in the JP1/Automatic Job Management System 3 Configuration Guide (in Windows) or 15.3.5 Using fully qualified domain names (FQDN) when using event jobs during DNS operation in the JP1/Automatic Job Management System 3 Configuration Guide (in UNIX).

Note that, by default, Receive JP1 Event jobs, Monitoring log files jobs, and Monitoring event log jobs obtain the host name of the host on which they are executed. These jobs then operate using the JP1/Base event server that has the same name as the host name they obtained. Therefore, to execute these jobs on an agent host that performs operations with the event server by using the FQDN event server name, set the FQDN agent host name or FQDN event server name used by JP1/AJS3 on the agent host. For details about how to set the names, see 6.3.17 Setting the event server name in the system using DNS in the JP1/Automatic Job Management System 3 Configuration Guide (in Windows) or 15.3.16 Setting the event server name in the system using DNS in the JP1/Automatic Job Management System 3 Configuration Guide (in UNIX).

If necessary, see 6.8.1 Canceling and re-setting service dependencies in the JP1/Automatic Job Management System 3 Configuration Guide and then set the JP1/AJS3 service dependencies.

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(2) Example of using FQDN host names when the DNS is used

This subsection shows an example of using FQDN host names to execute a job for agent hosts that have the same host name HostA, but have different IP addresses (100.0.0.200 and 200.0.0.200). In this example, the job has been assigned the execution host names HostA.hitachi_1.co.jp and HostA.hitachi_2.co.jp, and is entered from the manager host with host name HostM and IP address 100.0.0.100.

The example assumes that the hostname command executed on a manager host or agent host will return a host name in FQDN format. For details about the required setting when changing to FQDN host names, see (1) When to switch to using FQDN host names for event jobs above.

Figure 2‒39: Example of operation with FQDN host names

For this example, set the hosts files on the manager and the agent hosts in the local domain as follows (see (1) in the figure).

Note that the settings take effect in UNIX.

The hosts file at the manager:

Specify the following setting so that the name HostA can be resolved:
```
100.0.0.200 HostA.hitachi_1.co.jp
```
The hosts files at the agent (HostA on Hitachi_1.co.jp):

Specify the following setting so that the name HostM can be resolved:
```
100.0.0.100 HostM.hitachi_1.co.jp
```

In an environment in which neither of the DNS servers is able to resolve the host name of the other server, set the hosts files for both the manager and agent hosts as follows (see (2) in the figure).

The hosts file of the manager server on hitachi_1.co.jp:
```
200.0.0.200 HostA.hitachi_2.cojp
```
The hosts file of the agent server on hitachi_2.co.jp:
```
100.0.0.100 HostM.hitachi_1.co.jp
```

When you specify the above settings, manager host name HostM.hitachi_1.co.jp is sent to each agent host when the job is executed, and the agent hosts send a reply to HostM.hitachi_1.co.jp.

Cautionary notes

Use the manager host in an environment in which it can resolve the name of each agent host in FQDN format. Use the agents in an environment in which they can resolve the manager's name in FQDN format.
For host name resolution in a UNIX environment, the DNS must be searched before the hosts file. Otherwise, correct FQDN host names might not be acquired.
If you switch to FQDN host names, host names in FQDN format are used for the communication between manager hosts and agent hosts when event jobs are executed. If short local host names are defined in the jp1hosts information or jp1hosts2 information, the settings in the jp1hosts information or jp1hosts2 information take precedence over the DNS server. In that case, short host names are used for communication between manager hosts and agent hosts when event jobs are executed. If you define a short local host name in the jp1hosts information or jp1hosts2 information on an agent host, define the short agent host name in the jp1hosts information or jp1hosts2 information on the manager host. If you define a short local host name in the jp1hosts information or jp1hosts2 information on the manager host, define the short manager host name in the jp1hosts information or jp1hosts2 information on the agent hosts. For details about how to define jp1hosts information or jp1hosts2 information, see the JP1/Base User's Guide.
As long as the manager and agents operate within the same domain (hitachi_1.co.jp), it does not matter whether the value of DNSEstablish is Y or N. However, the manager host and agent hosts must operate in an environment in which the manager host and each agent host can resolve the name of the other hosts.

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(3) Notes on operation in a DNS environment

Note the following when using JP1/AJS3 in a DNS environment:

In a DNS environment, FQDN host names cannot be used for logical host names. Therefore, specify the settings so that IP addresses can be resolved from logical host names that are not in FQDN format. If you are considering using a cluster configuration for a system consisting of multiple domains, specify unique logical host names.
Run JP1/AJS3 in an environment in which the host names of agent hosts can be resolved as follows.
- When you specify Y for the environment setting parameter DNSEstablish, the host names of agent hosts are in the FQDN format.
- If you do not use DNS or you specify N for the environment setting parameter DNSEstablish, the host names of agent hosts are the ones that are output when you execute the hostname command.
When you set an alias host name as the execution agent for event jobs, make sure that the execution host name from which the alias has been defined can also be resolved on the manager host.
If a job has already been registered and the IP address cannot be resolved, job retry processing is performed. For details about this processing, see Table 2-3 Job retry process if a network error occurs in 2.2.2(4) Notes on manager/agent system configurations.
When you execute jobs on multiple hosts, specify settings that allow for the resolution of the IP addresses for the manager hosts, agent hosts, and the hosts in other systems.
When you obtain FQDN host names in an environment that uses the DNS, the case (upper or lower) of alphabetic characters in the host name might change each time it is obtained. The JP1/AJS manager used in such an environment is handled as another manager because the manager host name viewed from the agent has changed. This situation can lead to the following problems when an event job is executed.
- When the JP1/AJS3 service on the manager is restarted while a jobnet with a start condition is running, any monitored event that was detected after the restart is detected again.
- When the option to continue execution of active event jobs is enabled, if the JP1/AJS3 service on the manager is restarted in hot-start mode while an event job is running, multiple events are incorrectly detected as one event.
To prevent such problems, before you start operating JP1/AJS3 in a DNS environment, set a fixed manager name that will be used for communication between the manager and agent hosts. For details, see 6.3.15 Settings for ensuring that a fixed manager host name is used when event jobs are executed in the JP1/Automatic Job Management System 3 Configuration Guide (in Windows) or 15.3.15 Settings for ensuring that a fixed manager host name is used when event jobs are executed in the JP1/Automatic Job Management System 3 Configuration Guide (in UNIX). However, a fixed manager name is not necessary if you execute the jpoagoec command on the agent host on which event jobs are executed and the manager host names remembered by the agent are unique regardless of case.
To switch to operation that uses FQDN host names, use the procedure in 7.9.5 Changing to FQDN host names for event jobs in a DNS environment in the JP1/Automatic Job Management System 3 Administration Guide.
If you have switched to operation using FQDN host names, use the jp1ping command to make sure that the manager host is able to resolve agent host names and that the agent hosts are able to resolve the manager host name. For details about the jp1ping command, see the JP1/Base User's Guide.

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