North American Network Operators Group
Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical

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 <[email protected]> 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