SOA and trailing dot

[Barry Margolin]

In article <4.2.2.20000503170611.00c476e0 at nordic.cisco.com>,
Johnny Fribert Lauridsen  <jlaurids at cisco.com> wrote:
>Got this SOA via ls -d in nslookup - the DNS server is an MS DNS on NT:
>
>xxx.dk.                       SOA    abc.xxx.dk . (132 3600 300 172800 7200)
>  xxx.dk.                       NS     abc  
>
>stuff here from the DNS server and then at the end of the listing:
>
>  xxx.dk.                       SOA    abc.xxx.dk . (132 3600 300 172800 7200)
>
>                       
>
>1. What is the significant thing about not having the trailing dot '.' on
>the abc.xxx.dk in the SOA?

nslookup removes trailing dots in its output.  If you want to see things
precisely, use dig.

>2. Also, is it fully valid to only have a dot for the contact info? 

Not really.  It's supposed to be an email address with the "@" changed to
".".  So it should be something like hostmaster.cisco.com.

>3. The SOA is listed twice.  Is this significant, and why/how?

That's normal.  During a zone transfer, the SOA record is sent at the
beginning and the end.  This way, if the zone is modified while the
transfer is taking place (perhaps due to dynamic DNS updates) the slave
will notice the difference in serial numbers and ignore what it got
(because it contains a mixture of two versions) and try again.

-- 
Barry Margolin, barmar at genuity.net
Genuity, Burlington, MA
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