port number for zone transfer

[Barry Margolin]

In article <013EA3EDF4FACF11876600805F84CA3A01F549D8 at sieplan2.mel.ot>,
 <Dino.Chirico at ot.com.au> wrote:
>
>I am wanting to secure a DNS database behind a firewall and wanting to only
>allow zone transfers to pass through. I would like to know what the port
>number used for this process and is it UDP or TCP?? The zone transfer is to
>a secondary sever which will be a registered DNS server.

Zone transfer uses TCP port 53.  But before it does a zone transfer the
slave will first do an ordinary query for the SOA record, which uses UDP
port 53.

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