Escenario de estudio

All the DNS configuration files reside in the IFS directory

/QIBM/UserData/OS400/DNS and they are:

• Domain or forward mapping file (Domain_Name.DB): This file maps host names to IP addresses. The entries in this file are called resource records. This file has the same name as the domain with the .db extension.

Install 5769-SS1 O pt.31

O S/400 - Dom ain N ame System 1 QDN S library Q TO BD NS (*PG M ) Q TO BH 2N (*PG M ) Q TO BL KUP (*PG M) Q TO BX MIT (*PG M ) Q TO BX FER (*PG M) Q TO BM SG F (*MSG F) Q TO BM SG F (*ALRTBL) : : : CHG DNSA (*CMD) Q TO BJO BD (*JO BD)

2 Configure DNS Server_{with O peration Navigator}

ROO T.FILE TEMPLATE

A TT RIB U TE S

BO O T CA CHE

do main-name.DB (one or multiple) *.in-addr.arpa.DB (multiple) PID

• Reverse mapping files or (IP_address.in-addr.arpa.DB): These files map addresses back to host name. There is one file for each subnet address in the network where the domain’s hosts reside.

• Loopback address file (0.0.127.in-addr.arpa.db): This covers the loopback network used by the hosts to direct traffic to themselves.

• BOOT file (BOOT): This is the DNS server start-up file that ties all the DNS configuration files together.

Figure 6 shows the relationship between the BOOT file and the *.db files.

Figure 6. DNS Configuration Files Overview

2.4.1 Logging / Service Files

The following files are used to log DNS server activity and for problem determination:

• QUERYLOG: The DNS server logs every query in this file that it receives if it is configured to do so. To view the contents of the log, find it through Operations Navigator. The file name is QUERYLOG in the directory path

FileSystems\Root\QIBM\UserData\OS400\DNS for your AS/400 system. Carefully consider whether you need to log all queries and for how long. There is no limit to the size of the log file. Once you turn it on, it remains on until you disable logging and re-boot the DNS server. Figure 7 shows how to specify that you want the DNS server to log all the queries it receives in the QUERYLOG file.

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Figure 7. Configuring DNS Server Logging - QUERYLOG

• STATISTICS: Logs DNS server statistics. This summarizes the number of query hits the server received and the number of output packets it sent since the last time the server re-booted or reloaded its database. Delete this file when it becomes too large and you need to scroll down several times to find the information you are looking for. If you need to delete the file, you can find it through Operations Navigator. The file name is STATISTICS in the directory path FileSystems\Root\QIBM\UserData\OS400\DNS for your AS/400 system. Figure 8 shows how to display the DNS server statistics.

Figure 8. Displaying DNS Server Statistics

• DUMPDB: This file contains a dump of the DNS database for this server. You can use this database dump as a debugging tool to determine whether the DNS server is resolving IP addresses to host names correctly. You can match

property pages. The database dump includes the DNS server’s authoritative data and cache data as well as information about its root servers. Figure 9 shows how to display the dump of the DNS server database. Monitor the size of this file to prevent it from growing too large.

Figure 9. Displaying DNS Server Database

• RUNDEBUG: This file logs any debugging information. You can use Operations Navigator to find this file in

FileSystems\Root\QIBM\UserData\OS400\DNS for your AS/400 system. You must re-boot the server to have your changes take effect. Figure 10 shows how to specify the debug level.

If you specify the Debug level other than zero, the system continuously appends information to RUNDEBUG until you re-boot the server again. Monitor the RUNDEBUG file often enough to ensure that it does not grow too large for your needs. Information continually appends to this file until you delete the file.

• ATTRIBUTES: This file contains the DNS server version, debug level, and autostart attribute.

• PID: This file contains a process ID and it is used for DNS to send signals for Dump Database, Dump Statistics, and Update Server.

Figure 11 provides an overview of the DNS server jobs, files, and logs.

Figure 11. DNS Server Jobs, Files, and Logs

1. Start the DNS server.

2. The boot file provides start-up information: location of configuration files, server role (primary and/or secondary for specific domains), CACHE file with root name servers data, if acting as a secondary name server, the IP address of the primary master server to transfer zone data from, forwarders

information, and so on.

3. The DNS and zone transfer jobs start. 4. The name server is ready to answer queries.

5. DNS queries are logged in the QUERYLOG file if logging is turned on.