Linux - NetworkingThis forum is for any issue related to networks or networking.
Routing, network cards, OSI, etc. Anything is fair game.
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DNS queries are UDP based, so opening up port 53 (like with telnet) will not work. If you are asking about quering a DNS server in code, then take a look at: man resolver
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Originally posted by scowles
DNS queries are UDP based, so opening up port 53 (like with telnet) will not work.
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what do you mean with this?? telnet listens on port 23/tcp and hence uses connections...
dns servers listen on port 53/udp... the port needs to be open and accessible for them to work...
Sorry for the confusion. I did not really understand what the OP was asking (command line or code), so I was referring to using "telnet dns_server 53", which will not work since DNS queries are UDP based.
OK - so it uses UDP and UDP is a conectionless protocol. But how does that work, you send something to the DNS server and it sends a response, but there is no connection. So how does the program querying the DNS server know where to look for it?
I used telnet as an example, but as it only does TCP connections thats a bit useless. If I were to use socket proramming in C for example. Surely the commands you send to the DNS server are documented somewhere, I can't seem to find them anywhere though.
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