Internet Unknown (28)

Jonathan de Boyne Pollard J.deBoynePollard at Tesco.NET
Thu Nov 18 04:43:29 UTC 2004

MA> The nameservers are not RFC 1034 compliant (they don't
MA> reply to EDNS (RFC 2671) queries).

Not replying to queries is not a violation of the protocol.  There's no 
way that any protocol (such as DNS) that employs an unreliable transport 
(such as UDP) can make replying to messages a requirement.  It's wrong 
to say that a server that doesn't reply to queries is not complying with 
RFC 1034.

MA> You would think that all nameservers would handle EDNS queries by
MA> now. After all EDNS has been on the standards track for 5 years now.

The situation with EDNS0 is that because so few content DNS servers 
support it, the gain that EDNS0 gives from losing the DNS/TCP 
setup/teardown overhead in the small minority of cases is entirely 
offset by the loss incurred by the extra DNS/UDP traffic in the vast 
majority of cases.

As I have said before, the irony of this is that support for EDNS0 in 
content DNS servers is comparatively easy compared to support for EDNS0 
in the back ends of resolving proxy DNS servers and in DNS Client 
libraries.  If everyone merely did only the easy part of implementing 
EDNS0 support in their  content DNS servers (even if only supporting 
DNS/UDP datagram sizes up to 512 octets), the current situation would be 
much improved, and enabling the use of EDNS0 in a resolving proxy DNS 
server would no longer result in a net increase in network traffic.

MA> It only takes 1/2 a day to add support for them to a existing
MA> server.

That's a facile assertion.  How long it takes to add EDNS0 support 
obviously depends from the particular server software.  As I said, it 
also depends from the type of the server software.

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