Installing and Administering Internet Services

148 Chapter3
Configuring and Administering the BIND Name Service
Troubleshooting the BIND Name Server
(cname=0)
resend(addr=1 n=0) -> 128.59.32.1 6 (53) nsid=18 id=1 0ms
resend(addr=2 n=0) -> 128.59.40.130 6 (53) nsid=18 id=1 0ms
datagram from 15.19.10.14 port 4253, fd 6, len 41
req: nlookup(cucard.med.columbia.edu) id 1 type=1
req: found ’cucard.med.columbia.edu’ as ’columbia.edu’
(cname=0)
resend(addr=3 n=0) -> 128.103.1.1 6 (53) nsid=18 id=1 764ms
datagram from 128.103.1.1 port 53, fd 6, len 57
send_msg -> 15.19.10.14 (UDP 7 4253) ID=1
Following are detailed explanations of certain lines from this example.
req: nlookup(cucard.med.columbia.edu) id 1 type=1
This message was logged from the routine that handles requests. Shown
are the name looked up, the packet ID (used to determine duplicate
requests), and the type (as defined in /usr/include/arpa/nameser.h).
Type 1 is an address query.
resend(addr=1 n=0) -> 128.59.32.1 6 (53) nsid=18 id=1 0ms
Since no response came from 128.59.16.1, the query with nsid 18 was
resent to other servers.
datagram from 15.19.10.14 port 4253, fd 6, len 41 req:
nlookup(cucard.med.columbia.edu) id 1 type=1
Note that this came from the same IP address and port and has the same
length and ID as the preceding datagram. It is a duplicate and thus forw
discards it. These two lines are repeated three times throughout this
trace. The queries came from the same IP address and port, and have the
same ID and length in each case. Thus, these are all the same query. The
resolver sent the query three times because the name server didn’t
respond. The name server detects that the second and third are
duplicates and discards them. (We can tell because the duplicates did not
get to the forw line.)
Name Server Statistics
The name server keeps track of various statistics. You can print these
statistics to the file /var/tmp/named.stats by issuing the following
command:
/usr/sbin/sig_named stats