Query source port 53

[Bragi Baldursson]

I have been looking over the RFCs and the threads about the issue of using
source port 53 for querying and it seems to me
that the standard is to use port 53 as the query source port.
In a GPRS network environment we have typically 2 DNS servers.   Each of
these servers refer to a root
server who resides in a GRX environment to get info for resolving.

Now I have been having a problem with a particular GPRS operator that he
will not allow my DNS to query
his DNSs using source port 53.   My DNSs have always used source port 53
for querying so I was quite
taken aback by this.   His argument was that you are not allowed to use
port 53 as a source port for DNS
but you should use any port number > 1023.

Due to this they close their firewall for all DNS queries coming from
source port 53.    Is this correct?


Með kveðju/Best Regards
Bragi Baldursson
GPRS Kerfisverkfræðingur/GPRS Systems Engineer
Sími/Tel.:  +354 550 63 08    mailto:bb at siminn.is
Fax:  +354 550 62 39    www:http://www.siminn.is
Gsm:   +354 892 63 08

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