North American Network Operators Group
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Re: using TCP53 for DNS
- From: Stephane Bortzmeyer
- Date: Wed Apr 27 03:33:03 2005
On Tue, Apr 26, 2005 at 03:04:25PM -0400,
Patrick W. Gilmore <patrick@ianai.net> wrote
a message of 46 lines which said:
> I am interested in how many name servers - caching or authoritative
> - are filtering incoming and/or outgoing TCP port 53.
For authoritative name servers of TLD, you can browse:
http://www.generic-nic.net/dyn/mon/
And see that incoming TCP is often filtered, even on serious TLD:
w: Server doesn't listen/answer on port 53 for TCP protocol
* Ref: IETF RFC1035 (p.32 4.2. Transport)
The DNS assumes that messages will be transmitted as datagrams or in a byte stream carried by a virtual circuit. While virtual circuits can be used for any DNS activity, datagrams are preferred for queries due to their lower overhead and better performance.
* ns.cnc.ac.cn./159.226.1.1
* ns.cernet.net./202.112.0.44
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