Linux System Administration

BIND Tools

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Most DNS administrators use dig to troubleshoot DNS problems because of its flexi-

bility, ease of use, and clarity. Other lookup tools tend to have less functionality.

One alternative you should be aware of, however, is nslookup. We’ll also take a look

at rndc, a useful administration tool that’s included with BIND.

nslookup

nslookup works similarly to dig but is deprecated in Linux. Using it requires more

work, but you should be familiar with it because Microsoft Windows still uses it as

its primary lookup tool.

nslookup queries Internet domain nameservers in two modes: interactive and nonin-

teractive. The interactive mode allows you to query nameservers for information

about various hosts and domains, or to print a list of hosts in a domain.

The noninteractive mode simply prints the name and requested information for a

host or domain. For example, you could run the following lookup to find some infor-

mation about Google’s server:

# nslookup ns1.google.com

Server: 68.94.156.1

Address: 68.94.156.1#53

Non-authoritative answer:

Name: ns1.google.com

Address: 216.239.32.10

In interactive mode, nslookup provides a prompt where you can execute commands.

For example:

# nslookup

>

From the prompt you can do simple lookups, such as on an IP address:

> 70.253.158.42

Server: 172.30.1.2

Address: 172.30.1.2#53

Non-authoritative answer:

42.158.253.70.in-addr.arpa name = adsl-70-253-158-42.dsl.rcsntx.swbell.net. ...