Gandi.net Groups

Stephane - 

Mon ami qui bosse a rackspace me dit : 

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Ugh .... using UDP messaging is considered standard for name servers.
TCP is considered optional.  Mosso is in fact doing nothing wrong at
all.

I'll paste the relevant portion of that document here, with the
important bits highlighted with asterisks.  Note that the term
"datagrams" refers to UDP messages, not TCP.

---------------------------------

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*******.  Zone refresh
activities
must use virtual circuits because of the need for reliable transfer.

The Internet supports name server access using TCP [RFC-793] on server
port 53 (decimal) as well as datagram access using UDP [RFC-768] on UDP
port 53 (decimal).

4.2.1. UDP usage

Messages sent using UDP user server port 53 (decimal).

Messages carried by UDP are restricted to 512 bytes (not counting the IP
or UDP headers).  Longer messages are truncated and the TC bit is set in
the header.

UDP is not acceptable for zone transfers, ******** but is the
recommended method
for standard queries in the Internet.********  Queries sent using UDP
may be
lost, and hence a retransmission strategy is required.  Queries or their
responses may be reordered by the network, or by processing in name
servers, so resolvers should not depend on them being returned in order.

The optimal UDP retransmission policy will vary with performance of the
Internet and the needs of the client, but the following are recommended:

  - The client should try other servers and server addresses
    before repeating a query to a specific address of a server.

  - The retransmission interval should be based on prior
    statistics if possible.  Too aggressive retransmission can
    easily slow responses for the community at large.  Depending
    on how well connected the client is to its expected servers,
    the minimum retransmission interval should be 2-5 seconds.

More suggestions on server selection and retransmission policy can be
found in the resolver section of this memo.

...

que faire maintenant ? peux tu m'expliquer en plus de details pourquoi
le transport tcp est necessaire pour les domaines en .fr ? 

kaz