There are only two conditions when TCP will be used.......

1. the request packet from the host machine to the DNS erver is bigger than
512 bytes due to the fact that url is very long
2. when Two DNS servers are doing DNS zone transfers.


Else, the DNS traffic is always UDP no matter what. I have always put UDP
53 only for the exam.. :)..


http://www.ietf.org/rfc/rfc5966.txt


FNK


On Sun, Mar 11, 2012 at 6:48 PM, Eugene Pefti <[email protected]>wrote:

>  Guys,****
>
> Just a generic question. Would it be prudent to include a TCP port 53 as
> well if the question in the task asks about DNS traffic to be allowed
> through the firewall ? Or we should assume that hosts behind the firewall
> will do only UDP based queries ?****
>
> ** **
>
> Eugene****
>
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