Configuring BIND for Caching and Forwarding

After installing the BIND DNS server using YaST, you need to edit its main configuration file /etc/named.conf. When you are configuring BIND to act as a central DNS server for home or an organization, it is always a good idea to tap into your Internet service provider's DNS server as a resource to provide you with public DNS lookups. When you rely on another DNS server to go and find your DNS lookups, it is called a forwarder because it literally forwards your DNS lookups to another DNS server with the added benefit of caching the response so that future lookups of the data are returned locally by your DNS server.

Note BIND is available only with the Professional and Enterprise versions of SUSE. It is not avail able with the Personal edition.

To edit DNS server settings from now on, you will have to be logged in as the root user.

Tip You can also configure your DNS client and server through YaST. This chapter concentrates on direct configuration of the services so that you know how the system works. If you want > to configure a DNS server, start YaST and navigate to Network Services^ DNS Server. If you want to configure your DNS client, navigate to Network Services^ DNS and Host Name.

The important entry in /etc/named.conf is the forwarders declaration. A forwarder is a DNS server that your DNS server passes requests to when your DNS installation does not know the answer.

We have used two DNS servers for resilience purposes in this example, so that if the first DNS server is not contactable, the second will be used. Note that a semicolon separates the forwarders, and the line is delimited with a semicolon.

Note When a BIND server has been configured as a forwarder, it automatically caches any answers it receives from the Internet DNS servers. No extra configuration is needed to enable this caching functionality.

When the forwarders declaration is configured, start the nameserver with renamed: bible:~ # renamed start

Starting name server BIND 9 done

To automatically set named to start when your system boots, use chkconfig - a named.

Before you start testing the DNS server, you need to configure the system resolver. To do this, you need to edit the /etc/resolv.conf file. Change the nameserver entry to point to your newly created DNS server. In this case, this is

search nameserver

When the DNS server is started, you can look up a host name on the Internet to check that the forwarder and DNS are working correctly. The dig program is used to query a DNS server for information (see Listing 20-1), and we use it throughout this chapter for this purpose.

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