Re: [Fwbuilder-discussion] DNS explanation please?

[Vadim K. <va...@vk...>]

On Monday, October 13, 2003, at 08:07  AM, Stephe Campbell wrote:

> I am having a rather strange problem with DNS and hoped that someone 
> on the
> list could help me. I am seeing on our logs numerous requests for UDP 
> DNS
> having  the source port as UDP 53 instead of the destination port 
> being UDP
> 53. I realize that this is not the place for this question, but hope 
> someone
> would recognize the problem.
>
> I have read all over google about zone transfers and such taking place 
> on
> source port 53 to destination port 53, but the strangeness is that our 
> DNS
> server is request the source UDP 53 to an inside server on a high port 
> which
> is not a DNS server.
>

zone transfers use TCP rather than UDP, so if you see UDP port 53 its 
not a transfer. DNS queries sent by a name server should have source 
port 53, while DNS queries sent by a resolver have source port >1024 
because resolver is a library function that runs as  part of the 
regular unprivileged process which can not use ports below 1024. What 
you are seeing may be delayed DNS answers to queries sent by user 
processes on the inside server.

Can your internal server resolve names ? Do you see any strange 
timeouts or delays in its operation?

--vk


> Should I be worried? and thanks for any time and effort provided.
>
> Steve Campbell
> cam...@cn...
> Charleston Newspapers
>
>
>
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