Domain host TTL fields


Terry Slattery (tcs@USNA.ARPA)
Thu, 26 Feb 87 0:00:54 EST


Something that I've not seen discussed on this list is the optimum TTL
values for host entries, etc in the domain database. Anyone have any
numbers on the amount of traffic this stuff generates and the affect this
number has on network traffic?

For most large hosts, a minimum of 24 hours seems reasonable and 7
days would not be out of line. Small workstations that move around a
lot could have smaller values. Some hosts have a TTL value of 4 hours.
Is this really necessary? Administrators of zones should be able to
identify major hosts which don't change very often and increase the TTL
accordingly. The value could be reduced to a few hours prior to a change.

Also, what should be a good value for the nameserver timeout in waiting
for a reply. I've found that we typically time out two or three times
before receiving a reply. This means that several extraneous packets
are injected into the network each time we attempt to resolve an
address.

Am I'm missing some issues regarding these values?

        -tcs
        Terry Slattery U.S. Naval Academy 301-267-4413



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