6    BIND Service

The Berkeley Internet Name Domain (BIND) service is a distributed database lookup service that allows you to distribute the hosts database networkwide. A network running BIND does not have to be connected to the Internet; if it is, however, BIND allows systems on your network to resolve the names and addresses of hosts on the Internet.

This chapter describes the BIND environment, how to plan for BIND, how to configure your system for BIND, and how to manage BIND servers and clients.

For introductory information on BIND, see bind_intro(7).

6.1    The BIND Environment

In the BIND environment, systems can have the following roles:

• Primary server -- A system that is an authoritative source for information about a zone or zones and that maintains the master copy of the BIND database for the zone or zones.

  This system runs the named daemon, answers requests from clients and other servers, caches information, and distributes the databases to secondary servers.

• Secondary server -- A system that is an authoritative source for information about a zone or zones, but does not maintain the master copy of the BIND database for the zone or zones. Instead, a secondary server loads its database files from the primary server and periodically polls the primary server to ensure that its databases are up to date.

  This system runs the named daemon, provides backup for the primary server, answers requests from clients and other servers, and caches information.

• Slave server -- A server that might be an authoritative source for information about a zone or zones, but is restricted as to how it obtains information about zones for which it is not authoritative.

  This system runs the named daemon and answers queries from other servers and clients from its authoritative data and cache data. If the information is not present, it forwards queries to a list of systems called forwarders specified in its named.boot file. The queries are forwarded to each forwarder system until the list is exhausted or the query is satisfied. Slave servers store the information they receive until the data expires.

• Caching server -- A system that is not authoritative for any zones. This system runs the named daemon and services queries from other servers and clients by asking other servers for the information and caching the information it receives. Information is stored until the data expires.

• Client -- A system that queries a server for host name and address information, interprets responses, and passes information to requesting applications. The client is also called resolver. A client does not run the named daemon.

BIND runs on each system in your network. You must decide what role each system will play within the BIND environment that you are creating. For each domain, select one host to be the primary server; there can be only one primary server for each domain. Select one or more hosts to be secondary, slave, and caching servers. The rest of the hosts should run as BIND clients.

Figure 6-1 shows a domain in which there are two servers, one on each subnet, and multiple clients. The Host A server has primary authority for the zone and maintains the database files for the zone. The Host B server has secondary authority for the zone, obtaining a copy of the zone database from Host A and answering queries from clients.

Figure 6-1: Sample Small BIND Configuration

Figure 6-2 shows a domain in which there are three zones: mktg.corp.com, eng.corp.com, and acct.corp.com. Host B has primary authority for zone mktg.corp.com and secondary authority for each of the other two zones. Host C has primary authority for zone eng.corp.com and secondary authority for each of the other two zones. Host D has primary authority for zone acct.corp.com and secondary authority for each of the other two zones. Host A is both a router and a caching server. As a caching server, it caches information it receives from queries out of the parent domain.

Figure 6-2: Sample Large BIND Configuration

6.2    BIND Planning

Appendix A contains a worksheet that you can use to record the information that you need to provide to configure BIND. If you are viewing this manual online, you can use the print feature to print a copy of this part of the worksheet.

Figure 6-3 shows Part 5 of the Configuration Worksheet. The following sections explain the information you need to record in Part 5 of the worksheet.

Figure 6-3: Configuration Worksheet, Part 5

Local domain name

The parent domain name of which your local system is a part. For example, if your system's domain name is cxcxcx.abc.xyz.com, your local domain name is abc.xyz.com.

6.2.1    Server

Scope

If you want to restrict your system to query a specific list of systems (forwarders) only, check SLAVE; otherwise, check MASTER.

Host resolution order

The first source in resolving host name queries on your system. If you want to query BIND first, check FIRST. If you want to query the /etc/hosts file first, check SECOND.

Forwarder name

The host name of a system or systems to which your server will forward queries, which it cannot resolve locally. When the server receives a query that it cannot answer from its cache, it sends the query to a forwarder for resolution. If the forwarder cannot answer the query, the server might contact other servers directly. If you checked SLAVE in the Scope field, you must write down some forwarder names; otherwise, forwarders are optional.

Zone domain name

The domain name of the top-level domain in the zone.

Authority

If the server is a primary authority for information about the zone (maintains the zone database file), check PRIMARY. If the server is a secondary authority for information about the zone, check SECONDARY.

Data file

For a server that is a primary authority for information about a zone, the pathname of the file that is the master copy of zone information.

For a server that is a secondary authority for information about a zone, the pathname of the file that is to contain zone information obtained from the primary server. This is optional, but useful when the server is restarted. Instead of waiting to obtain information from a primary server, which might not be available, the secondary can restart using the information in the data file.

Server address

For a server that is a secondary authority for information about a zone, the address of the server that has primary authority for the zone domain.

6.2.2    Client

Server name

The name of a server to contact for host name resolution. Specify up to three.

Internet address

A corresponding IP address for the server.

Host name resolution

The first source in resolving host name queries on your system. If you want to query BIND first, check BIND. If you want to query the /etc/hosts file first, check /etc/hosts.

6.3    Configuring BIND

Digital recommends that you use the BIND Configuration application of the Common Desktop Environment (CDE) Application Manager for configuring BIND on systems with graphics capabilities. You can configure the following systems:

• Primary server

• Secondary server

• Caching server

• Slave server

• Client

See bindconfig(8X) for more information on the BIND Configuration application.

To invoke the BIND Configuration application, log in as root and do the following:

1. Click on the Application Manager icon on the CDE front panel.

2. Double-click on the System_Admin application group icon.

3. Double-click on the Digital System_Management_Utilities application group icon.

4. Double-click on the Configuration application group icon.

5. Double-click on the BIND Configuration application icon. The BIND Configuration main window appears, showing available BIND service types and configured BIND service types.

Note

You must first set up the primary server; then, you can configure the other systems in any order.

To exit the BIND Configuration application, choose File then Exit.

Note

For systems without graphics capabilities, you can use the bindsetup utility. See bindsetup(8) for more information.

The BIND Configuration application also has an extensive online help system. You can use it instead of the instructions in this section to configure BIND on your system.

6.3.1    Configuring a BIND Server

To configure a server, do the following:

1. In the BIND Configuration main window, select Server from the Available BIND Services Types field.

2. Click on Configure. The Configure Server dialog box appears.

3. Click on the appropriate radio button in the Scope field. If you click on the Slave radio button, go to step 11.

4. Enter the domain name in the Local Domain input text box.

5. Indicate the order in which to resolve host name queries in the Host Name Resolution field. Click on the First radio button if you want to query BIND before checking the /etc/hosts file. Click on the Second radio button if you want to check the local /etc/hosts file before querying BIND; this is recommended.

   Alternatively, you can run the svcsetup script to customize service order selection. See Section 6.4 and svcsetup(8) for information on modifying the svc.conf file.

6. If your system does not have authority for any zone, go to step 11.

7. For servers that have authority for a zone or zones, do the following:

   1. Click on Zones. The Zones Served dialog box appears.

   2. Click on Add. The Add Zone dialog box appears.

   3. Enter the domain name in the Domain text box.

   4. Click on the Primary radio button if this system is a primary nameserver for this zone. Click on the Secondary radio button if this system is a secondary nameserver for this zone.

   5. If you are primary or secondary authority for this zone, enter the name of the zone data file in the Data File input text box. If you are using an existing /etc/hosts file to create the database, this is the name of the data file you create after you exit the BIND Configuration application.

   6. If you are secondary authority for this zone, enter the IP address of the primary server in the Server Addr input text box.

   7. Click on OK. This accepts the configuration, adds the zone to the list of zones served, and closes the Add Zone dialog box. Repeat the second step and all subsequent steps in this sublist for other zones for which you have authority.

   8. Click on OK. This accepts the configuration and closes the Zones Served dialog box.

8. If you want to forward queries to a specific server or servers (forwarders) for resolution, do the following:

   1. Click on Forwarders. The Forwarders dialog box appears.

   2. Enter the name or IP address for the new forwarder in the Forwarder input text box. If you enter a host name, it must be included in the /etc/hosts file.

   3. Click on Insert. This places the new forwarder address at the end of the list. Repeat the previous step for each forwarder.

   4. Click on OK. This accepts the list of forwarders and closes the Forwarders dialog box.

9. If you want to start the named daemon, do the following:

   1. Click on name daemon. The Configure Named Daemon dialog box appears.

   2. Click on OK. This accepts the configuration, starts the named daemon, and closes the Configure named Daemon dialog box.

   If you do not want to start the named daemon now, use the following command to start the daemon manually in a terminal window after you are finished with the BIND Configuration application:

   #  /sbin/init.d/named start
   

10. Click on Commit. This accepts the configuration and closes the Configure Server dialog box.

You can also modify your server configuration. See the BindConfig application online help and bindconfig(8X) for more information.

If your system is a primary authority for information about a zone or domain and you want to create the database from an existing hosts file, do the following:

1. Copy the hosts file that you want to convert to the BIND hosts database into the /etc/namedb/src directory.

   To create the source file from which the hosts database will be created, update the primary server's local /etc/hosts file and then copy it into the /etc/namedb/src directory. Note that if a system, host1 for example, is in your BIND domain and is running BIND but is not included in the primary server's hosts database, other systems in the domain cannot obtain the IP address of host1.

   Example 6-1 is a list of sample /etc/hosts file entries.

   Example 6-1: Sample /etc/hosts File

   127.0.0.1 localhost
   120.105.5.1 host1
   120.105.5.2 host2
   120.105.5.3 host3
   120.105.5.4 host4
   120.105.5.5 host5
   

   Note

   Note that the file that you copy into the /etc/namedb/src directory must be named hosts.

2. To convert the hosts file in /etc/namedb/src directory to the appropriate BIND format, enter the following commands:

   #  cd /etc/namedb
#  make hosts
   

6.3.2    Configuring a BIND Client

To configure a BIND client, do the following:

1. In the BIND Configuration main window, select Client from the Available BIND Services Types field.

2. Click on Configure. The Configure Client dialog box appears.

3. Enter the domain name in the Local Domain input text box.

4. Click on the Host Name text field and enter a host name for the nameserver.

5. Click on the Address text field and enter the IP address for the nameserver.

   The addresses are placed in the /etc/resolv.conf file, where the resolver uses them to determine the IP addresses of name servers it should query.

6. Click on the appropriate button to add the host name to the list of name servers. If the address is not in the /etc/hosts file, a dialog box appears asking you if you want to add it. To add other nameservers, go to step 4 and repeat the steps that follow.

7. Indicate the order in which to resolve host name queries in the Hostname Resolution Order field. Click on the First radio button if you want to query BIND before checking the /etc/hosts file. Click on the Second radio button if you want check the local /etc/hosts file before querying BIND; this is recommended.

   Alternatively, you can run the svcsetup script to customize service order selection. See Section 6.4 and svcsetup(8) for information on modifying the svc.conf file.

8. Click on Commit. This accepts the configuration and closes the Configure Client dialog box.

You can also modify your client configuration. See the BindConfig application online help and bindconfig(8X) for more information.

6.4    Modifying the svc.conf File with svcsetup

You can modify the /etc/svc.conf file without running the BIND Configuration application. To do this, you invoke the svcsetup script using the following command:

#  /usr/sbin/svcsetup

Once invoked, use the following steps to edit the /etc/svc.conf file:

1. Press Return following the informational messages to continue.

2. Press Return to choose the m option from the Configuration Menu.

3. Choose option 2 from the Change Menu.

   Option 2 corresponds to the hosts database.

4. Enter the number that corresponds to the order in which you want the services running on your system queried for hosts data.

   Listing local first means that the local /etc/hosts file is searched first for the requested information. If the information is not found locally, then BIND servers, NIS servers, or both, are queried, depending on which options you choose.

   Note

   Digital recommends that local be the first service that your system queries for all databases, regardless of what services you are running.

   Choose option 3, 4, 5, or 6 to configure the svc.conf file so that BIND serves hosts information.

   The svcsetup script indicates that it is updating the /etc/svc.conf file. When svcsetup is finished updating the file, notifies you and returns you to the system prompt (#).

6.5    Updating BIND Data Files on the Primary Server

Occasionally you may need to update the BIND data files; for example, you may need to add a host to the data files. To do this, use the bindconfig application as follows:

1. In the BIND Configuration main window, select Server from the Available BIND Services Types field.

2. Click on Modify. The Configure Server dialog box appears.

3. Click on Zones. The Zones Served dialog box appears.

4. Click on the zone whose data file you want to modify from the list.

5. Click on Modify. The Modify Zone dialog box appears.

6. Click on Resource Record. The Resource Record dialog box appears.

7. Click on Add. The Add Resource Record dialog box appears.

8. Choose the parameters you want.

9. Click on OK. The Add Resource dialog box closes and the new resource record is added to the list of resource records.

10. Click on OK. The Resource Record dialog box closes.

11. Click on OK to close the Zones Served dialog box.

12. Click on Commit to close the Configure Server dialog box.

Alternatively, to update a data file, you can do the following:

1. Edit the /etc/namedb/src/hosts file to add the new host.

2. Change to the /etc/namedb directory and enter one of the following commands:

   #  make hosts
#  make all
   

After you edit the hosts file and enter the make command, the BIND conversion scripts (which are in the /etc/namedb/bin directory) do the following for you:

1. Create the new hosts databases: hosts.db and hosts.rev.

2. Place the new databases in the /etc/namedb directory.

3. Send a signal to the named daemon to reload all databases that have changed.

Note

If you have manually entered mail exchanger (MX) records in the hosts.db file, these records are lost. You will have to edit the hosts.db file and add the MX records.

The BIND database conversion scripts also increment the serial number field of the start of authority (SOA) entry in the database file. When the secondary servers poll the primary server and see that the serial number field has changed, they know to refresh their data.

The process is the same for all of the valid files in the primary server's /etc/namedb/src directory.

Scripts are provided to create the following databases: hosts.db and hosts.rev.

6.6    Obtaining Host Name and IP Address Information

There are several ways that you can obtain information about host names, IP addresses, and user information from a system using the BIND service. The following sections provide an introduction to two commands: nslookup and whois.

6.6.1    The nslookup Command

You can use the nslookup command to noninteractively and interactively query the BIND service for information about hosts on the local, as well as remote, domains. You can also find information about BIND resource records such as mail exchanger (MX), name server (NS), and so forth.

For a noninteractive query, use the following syntax:

nslookup hostname

The output is the server name and address and the host name and address.

For an interactive query, use the following syntax:

nslookup

The output is the default server name and address and the nslookup prompt, a greater than sign (>).

For example, to obtain information about MX, you need to query nslookup interactively, supplying a valid domain name. The following example shows how to find who takes mail for the domain corp.com:

#  nslookup

Default Server:  localhost
Address:  127.0.0.1

Server:  localhost
Address:  127.0.0.1
findmx.corp.com      preference = 100, mail exchanger = gateway.corp.com
gateway.corp.com     inet address = 128.54.54.79

A good way to learn how to use the nslookup command is to experiment with it. To obtain a list of the interactive nslookup command options, enter a question mark (?) at the nslookup prompt. For further information, see nslookup(1).

6.6.2    The NIC whois Service

The Network Information Center (NIC) whois service allows you to access the following information about a domain:

• The name of the domain

• The name and address of the organization responsible for the domain

• The domain's administrative, technical, and zone contacts

• The host names and network addresses of sites providing the BIND service for the domain

• The registered users in the domain

For example, to use the NIC whois service to obtain information about a domain named digital.com, use the whois command and specify the domain name as follows:

#  whois digital.com

Digital Equipment Corporation (DIGITAL2-DOM)
   250 University Avenue
   Palo Alto, CA 94301-1616
   Domain Name: DIGITAL.COM

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.
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The InterNIC Registration Services Host ONLY contains Internet Information
(Networks, ASN's, Domains, and POC's).
Please use the whois server at nic.ddn.mil for MILNET Information.