Re: Do DNS Servers cache?

Ric Castagna ( )
Fri, 10 Apr 1998 14:14:34 -0400

>I have also seen it suggested that if you know ahead of time that you will
>be doing some dns updates, shorten the TTL in the SOA record so that when
>you make changes they will be updated more quickly.

Qualifier for the following statements: I do not use the MS DNS manager
that comes with NT4.0. I personally have found it difficult to understand
and implement. I use a freeware port of BIND for DNS ( on
my NT machines, and BIND on UNIX machines as well. That way I've got some
consistancy in my records.

You should also verify that you are increasing the serial number, and then
reloading the DNS tables after you make changes to your records.

When you increase the serial number and reload the tables, you will be able
to get an Authoritative response the first time you request the record.

For serial numbers, I use the scheme 'yyyymmddxx' (1998041001) increasing
the value 'xx' each time I change the particular record. I figure that the
possibility of 99 revisions to a single DNS record ought to be adequate. If
they're not, I've got no business playing in DNS.