BIND 9 - DNS server gets an Error: 1 (Format Error) reply for every first query sent

Jim Reid jim at rfc1035.com
Thu Dec 4 19:16:49 UTC 2003


>>>>> "Elias" == Elias  <elias at streamyx.com> writes:

    Elias> Hi BIND gurus, I've just tried using BIND 9 and have
    Elias> noticed something strange. Why is it that everytime my DNS
    Elias> server first sends out a query, the remote DNS server will
    Elias> respond with a format error? After getting the error reply,
    Elias> my server will send another query and this time it gets
    Elias> accepted.

This is normal. It's nothing to worry about. BIND9 tries to use EDNS0
by default: essentially DNS with bigger packets and more header bits.
Old servers don't support EDNS0. So they reject BIND9's EDNS0 probes,
usually with a FORMERR (Format Error) because they don't understand
EDNS0 packets. BIND9 then repeats this query with RFC1035-style DNS
packets and makes a note to always do this when speaking to that other
name server.

This is also explained in the BIND9 migration notes.

If BIND9's behaviour annoys you, EDNS0 can be switched off on a per-server
basis with server{} statements in named.conf. Consult the ARM for more
details.


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