Time values in zone files

[bmanning at ISI.EDU]

> 
> This is more a question of procedure...
> 
> I was just wondering what the basis is for choosing various time values in
> the zone files.  Basically when to choose what value and when not to choose
> another.
> 
> Thanks
> - Bennett

Time Values?   One presumes you are talking about the various time intervals
that are only found in the SOA record and the (relatively) new $TTL directive
which is also a time interval.

Basically choose small values when you are going to change things and you 
need to have the changes propogated quickly and larger values when you want
persistance in your caches & slaves.  YMMV. The Net will change. Topology
shifts. Thats why these are tunable parameters.

Here is one example from a zone I manage:

                       1998081900      ; Serial
                        10800   ; Refresh - 3hrs
                        900     ; Retry   - 15min
                        604800 ; Expire  - 1000hrs
                        86400 ) ; Minimum - 24hrs

Note that the serial is a 32bit unsigned number and is compared using sequence
space arithmatic. 

Other than those, I don;t think there are "time values" in the DNS.

-- 
--bill