Installing and Administering Internet Services

Chapter 3 109
Configuring and Administering the BIND Name Service
Troubleshooting the BIND Name Server
10.The /etc/hosts file, NIS, or NIS+ contains incorrect data. The
name service switch (/etc/nsswitch.conf) allows host name
lookups in /etc/hosts, NIS, or NIS+ and one of those databases
contains incorrect data. For information on configuring the
/etc/hosts file, see “To Edit the /etc/hosts File” on page 36. For
information on NIS and NIS+, see Installing and Administering NFS
Services.
Understanding Name Server Debugging
Output
To diagnose problems in the debugging output of the name server, you
need to know what output from a successful query looks like. The
following two examples show output from successful host name lookups.
The first example does not involve any retransmissions, while the second
example does. Note that debugging output looks the same whether it
comes from a primary, secondary, or caching-only server.
Example 1: No Retransmissions
Debug turned ON, Level 1
datagram from 15.19.10.14 port 4258, fd 6, len 35
req: nlookup(john.dept.inc.com) id 1 type=1
req: found ’john.dept.inc.com’ as ’inc.com’ (cname=0)
forw: forw -> 192.67.67.53 6 (53) nsid=29 id=1 0ms retry 4 sec
datagram from 192.67.67.53 port 53, fd 6, len 166
resp: nlookup(john.dept.inc.com) type=1
resp: found ’john.dept.inc.com’ as ’inc.com’ (cname=0)
resp: forw -> 15.19.11.2 6 (53) nsid=32 id=1 0ms
datagram from 15.19.11.2 port 53, fd 6, len 119
resp: nlookup(john.dept.inc.com) type=1
resp: found ’john.dept.inc.com’ as ’dept.inc.com’ (cname=0)
resp: forw -> 15.19.15.15 6 (53) nsid=33 id=1 0ms
datagram from 15.19.15.15 port 53, fd 6, len 51
send_msg -> 15.19.10.14 (UDP 7 4258) id=1
Debug turned OFF, Level 1
• In the first group of four lines, a query is received for
john.dept.inc.com. The query is forwarded to a root server,
ns.inc.ddn.mil at address 192.67.67.53
• In the second group of four lines, ns.nic.ddn.mil responded with
NS records for inc.com.