Re: Why does DNS.EXE listen on a ephemeral TCP port?

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"Kevin D. Goodknecht Sr. [MVP]" <admin@xxxxxxxxxxxxxx> wrote:

DNS listens on both UDP and TCP 53, but when a DNS server sends a query to
another server on port 53, the response comes back on an ephemeral port,
which DNS also listens on.

For UDP, I agree. But not for TCP. The status for the ephermeral port
from which a (client) machine originates a TCP connection should never be
listening. The listening status is reservered for the server. In this
case DNS is listening on a high TCP port and a client would have to connect
to it. I want to know in what case a client (another DNS server making a
query would be considered a client) would connect to my server on a TCP port
other that 53, and how does that client know to do so.

Thanks for your input!

Brian




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