What is the sense of telnet on 53 port?
Brad Knowles
brad.knowles at skynet.be
Fri Jul 27 01:26:25 UTC 2001
At 11:25 AM -0700 7/26/01, Kankossa wrote:
> I'm installating a DNS server. Can I use telnet on port 53 from any
> machine is considered as a test of DNS?
Nope.
> Or it has no sense since DNS
> is UDP protocole while telnet is a TCP protocole?
No, DNS packets can be transmitted over either TCP or UDP.
However, it is not a plaintext format, but a binary format.
Therefore, you cannot use a telnet plaintext application to
communicate directly on port 53. Instead, you need to use DNS query
and debugging utilities, like dig, doc, dnswalk, etc....
> Then if I connected
> to to the server, what this means?
It accepted a TCP connection, but then didn't know what to do
with a client that spoke a different protocol.
> More preciously my troubles are:
> - Is "telnet IP_AD 53" where IP_AD is the IP addresse of my DNS
> machine means that my DNS Works?
Nope.
> - Is "telnet FQDN 53" where FQDN my be any domaine on the net prove
> that my DNS works fine?
Nope.
> PS: I know that nslookup exist and my be more appropriated, but I want
> to know about the above questions.
IMO, nslookup is evil. It should be avoided unless you have
specific reason to know you want to use it. Use dig instead.
--
Brad Knowles, <brad.knowles at skynet.be>
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