5.8 Monitoring DHCP

After configuring your DHCP servers and beginning to provide DHCP services, you can also perform auditing or generate SNMP traps.

Deciding which DHCP options to use depends on your implementation. See DHCP Options for information about available DHCP and BOOTP options.

5.8.1 Events and Alerts

You can configure the DHCP servers to maintain a history of server activity in the events log. Events are activities that are considered significant, such as loading or unloading the server or problems the server encounters. The events logged depend on the parameters set on the server.

You can configure DHCP servers to log major events, all events, or none (the default).

Event logs can be saved for future reference. When you are logging events, it is important to pay attention to the event log size. Event logs grow rapidly, especially if you are experiencing or researching problems. Event logs should be maintained or purged regularly to control the amount of disk space used. You can launch the CSAUDIT management utility by typing CSAUDIT at the server console.

See Viewing the DHCP Event Log for more information about viewing and saving the DHCP event logs using the iManager utility.

See Viewing or Saving the DHCP Event Log for more information about viewing and saving the DHCP event logs using the Java-based Management Console.

5.8.2 Auditing Server Activity

The audit trail log records a history of activity logged by DHCP servers. You can use the audit trail log to diagnose network trends. A DHCP audit trail would include a history of address assignments, including which host had an address during a given period of time, and a list of addresses that were in use when pinged.

See Configuring DHCP Auditing for information about configuring DHCP auditing using the iManager utility.

See Configuring DHCP Auditing for information about configuring DHCP auditing using the Java-based Management Console.

5.8.3 DHCP SNMP Events

Following are examples of DHCP SNMP events logged/trapped for SNMP event generation and the severity level that can be associated with them.

Minor events

  • A decline generated against an IP address.
  • All logged file transactions have been reprocessed (operational).

Warning events

  • An eDirectory update to the subnet failed, causing degraded operation (incomplete transactions are logged to a local file named dhcplog.log).
  • SNMP recovered from an internal fault and the error code was logged.
  • A subnet was not configured and addresses are not available, causing degraded operation.

Major events

When the dhcpsrvr.nlm is loaded and the server is operational and ready for LAN-based clients, the following events are logged or trapped for SNMP event generation:

  • Found unknown subnets with prior records.
  • The eDirectory objects are not synchronized.
  • A DNS update for adding a resource record is dropped.
  • A DNS update for deleting a resource record is dropped.
  • An unknown zone with resource records have been found.

Critical events

  • The logger fails to open the recovery log file or is having difficulty in opening it (the server is inoperative).
  • The main thread fails to process the lease expiration (the server is inoperative).
  • The server detects a configuration change in the directory.