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9-2
DHCP Client Configuration
9.1 Protocol Timing
The timing behaviour of the client need not be configured by the user. If no
timing configuration is provided by the user, a reasonable timing
behaviour will be used by default - one which results in timely updates
without placing an inordinate load on the server. The following statements
can be used to adjust the timing behaviour of the DHCP client if required:
9.1.1 Timeout
timeout
tim
e;
The timeout statement determines the amount of time that must pass
between the time that the client begins to try to determine its address and
the time that it decides that it is not going to be able to contact a server. By
default, this timeout is sixty seconds. After the timeout has passed, if there
are any static leases defined in the configuration file, or any leases
remaining in the lease database that have not yet expired, the client will
loop through these leases attempting to validate them, and if it finds one
that appears to be valid, it will use that lease's address. If there are no valid
static leases or unexpired leases in the lease database, the client will restart
the protocol after the defined “retry” interval.
9.1.2 Retry
retry
tim
e;
The retry statement determines the time that must pass after the client has
determined that there is no DHCP server present before it tries again to
contact a DHCP server. By default, this is five minutes.
9.1.3 Select-timeout
select-timeout tim e;
It is possible (some might say desirable) for there to be more than one
DHCP server serving any given network. In this case, it is possible that a
client may be sent more than one offer in response to its initial lease
discovery message. It may be that one of these offers is preferable to the
other (e.g., one offer may have the address the client previously used, and
the other may not).
The select-timeout is the time after the client sends its first lease discovery
request at which it stops waiting for offers from servers, assuming that it
has received at least one such offer. If no offers have been received by the
time the select-timeout has expired, the client will accept the first offer that