port 53 tcp/udp

[nex6]

* Mark Andrews <marka at isc.org> [2012-07-18 07:43:34 +1000]:

> 
> In message <20120717194840.GA3773 at glasya2>, nex6 writes:
> > when does bind or dns in general use tcp and when does it use udp?
> 
> When it needs to.  TCP support is NOT optional.
>  
> > from what i have read, from the client intial request if under 512b
> > come in on UDP port 53, if and depending on the local
> > resolver in needs to retry it *could* be a tcp port 53 request?
> > 
> > now thats client to name server;
> > 
> > 
> > what about, recursive lookups? or forwarded requests? etc 
> 
> It's still client to server.  Recursive servers have a client side
> and a server side.
> 
> > how does that work?
> 
> Exactly the same why.
>  
> > -Nex6

Thanks for the reply, i have an internal client with there own NS that is blocking TCP port 53, and complaining of random
issues. like our NS not sending them traffic randomly.....

I told them to unblock port 53 tcp.... then call me....



> > 
> > 
> > _______________________________________________
> > Please visit https://lists.isc.org/mailman/listinfo/bind-users to unsubscribe from this list
> > 
> > bind-users mailing list
> > bind-users at lists.isc.org
> > https://lists.isc.org/mailman/listinfo/bind-users
> -- 
> Mark Andrews, ISC
> 1 Seymour St., Dundas Valley, NSW 2117, Australia
> PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org