serial number format in dynamic dns update

Simon Hobson shobson0309 at
Thu Oct 7 15:16:55 UTC 2004

Norman Zhang wrote:
>  >RFC suggests that serial number in SOA, should be in
>>the format of YYYYMMDDnn.
>>How dyn.dns updates the serial number using this
>>What is the next serial number using dyndns update, if
>>the current serial number is '2004103199'?
>I'm not sure if this has been discussed, Verisign is pushing for a new
>In bind 9.2.3 and dhcp 3.0.1, I can only use yyyymmdd format. Is this by

Well with Bind 9.2.2 and dhcp 3.0.1 (what I'm running here) there is 
no such constraint - DHCPD doesn't know or care what the serial 
number is. As far as Bind is concerned (and I assume any RFC 
compliant DNS server) the serial number is just a number, nothing 
more, nothing less. If it HAPPENS to be something 'human friendly' 
then that's a plus, but Bind just doesn't care - to it 2004100700 is 
just a large integer (0x7774265c if I've got it right !). As long as 
it keeps getting larger (whether by 1 to 2004100701 or by 100 to 
2004100800) then no-one actually cares !

What verisign are saying doesn't affect this - they are merely 
recognising that with the new update regime, they are likely to 
exceed 100 updates/day and so the ddddmmyyxx format would break down, 
so they are simply reverting to treating the serial number as a 
number and have chosen to use the unix time in seconds which is a) 
guaranteed to increase until 2038, and b) can be translated to a time 
in case anyone did want to work out when an update occurred.

If you use DDNS, you CAN use yyyymmddxx (but the date will become 
meaningless over a while), you CAN do the Verisign method, or you CAN 
just start at ONE and keep incrementing - BIND DOESN'T CARE !



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