Installing and Administering Internet Services

276 Chapter6
Dynamic Host Configuration Protocol (DHCP)
Monitoring and Troubleshooting DHCP Operations
• Is the reply appropriate for the client?
Table 6-1 lists some of the common error messages you may see in the
syslog when a client fails to get an address lease.
Tracing DHCP Packet Flow
Turn on tracing by typing the following command:
/usr/sbin/dhcptools -t ct=100
This command turns on tracing and writes the full contents of 100
packets to a file named/called /tmp/dhcptrace.
NOTE You must always use the ct=NN option, because the default number of
packets to trace is zero. The maximum number of packets to trace is 100.
Dumping the Internal State of the Daemon
Use the dhcptools to cause the daemon to dump. Type the following
command:
/usr/sbin/dhcptools -d
This command dumps dynamic information into the file
/tmp/dhcp.dump.other. Other information is dumped into the files
Table 6-1 Common Errors Found in Syslog
Error Cause
304 A client requests an address on a subnet not available or
accessible from this DHCP server. The client gets no response
from this server.
305 The pool or device group is full. That is the DHCP server has
handed out all the addresses available. The client gets no
response from this server.
308 An illegal packet received.
316 The DHCP server knows nothing about the client lease or forgot
about the lease. In this case, the client will fall back to request a
brand new lease.