Valid Serial and Expire?

Barry Margolin barmar at
Wed Nov 3 19:33:20 UTC 1999

In article <381fd47f at>, M & J <mhutch at> wrote:
> 1999110201 ; serial
>                        8 ; refresh
>                        2 ; retry
>                        1 ; expire
>                        1 ; default_ttl
>Is this a valid set of records?  I updated the serial to today.  The problem
>I am experiencing this that the world can no longer see to my name server.

All the timeouts are awfully low.  You realize they're expressed in
seconds, don't you?

Having Expire less than Refresh is a bad idea; Expire should usually be a
long time, like a week or month.  The way you have it, the slave servers
will expire the zone before they try to refresh it.  And refreshes are
never done more often than every 15 minutes, so the zone will be expired
for 14 minutes, 59 seconds out of every 15 minute period.  Refresh rate is
typically an hour.

The low default TTL means that there will effectively be no caching of your
records; almost every time a remote server needs to look up something in
your domain, it will have to query one of the authoritative servers.
Typical TTLs range from an hour for data that's likely to change, to a day
or two for more static data.

Barry Margolin, barmar at
GTE Internetworking, Powered by BBN, Burlington, MA
Please DON'T copy followups to me -- I'll assume it wasn't posted to the group.

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