SERVFAIL when two SOA in the domain

[Mark Andrews]

In message <20130829182253.GA13085 at laperouse.bortzmeyer.org>, Stephane Bortzmey
er writes:
> One of my contacts noticed that you cannot query 42.fr's SOA with
> BIND: SERVFAIL. Querying other types, or using Unbound (or Google
> Public DNS) instead of BIND works.
> 
> The only thing special he sees is the double SOA:
> 
> % dig SOA 42.fr
> 
> ; <<>> DiG 9.9.2-P1 <<>> SOA 42.fr
> ;; global options: +cmd
> ;; Got answer:
> ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 9894
> ;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 2, ADDITIONAL: 1
> 
> ;; OPT PSEUDOSECTION:
> ; EDNS: version: 0, flags: do; udp: 4096
> ;; QUESTION SECTION:
> ;42.fr.				IN	SOA
> 
> ;; ANSWER SECTION:
> 42.fr.			2907	IN	SOA	ns1.42.fr. postmaster.4
> 2.fr. 2013032901 300 300 604800 86400
> 42.fr.			2907	IN	SOA	ns2.42.fr. postmaster.4
> 2.fr. 2013032901 300 300 604800 86400
> 
> ;; AUTHORITY SECTION:
> 42.fr.			2897	IN	NS	ns1.42.fr.
> 42.fr.			2897	IN	NS	ns2.42.fr.
> 
> ;; Query time: 0 msec
> ;; SERVER: 127.0.0.1#53(127.0.0.1)    <----- Unbound
> ;; WHEN: Thu Aug 29 20:21:51 2013
> ;; MSG SIZE  rcvd: 153
> 
> I'm not sure of what the RFC say about that...
> 
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Named will reject answers which contain multiple non-identical
records at the same name and type that should be singletons.  The
list of types with that attribute is below.

% grep SINGL lib/dns/rdata/*/*.c
lib/dns/rdata/generic/cname_5.c:	(DNS_RDATATYPEATTR_EXCLUSIVE | DNS_RDATATYPEATTR_SINGLETON)
lib/dns/rdata/generic/dname_39.c:#define RRTYPE_DNAME_ATTRIBUTES (DNS_RDATATYPEATTR_SINGLETON)
lib/dns/rdata/generic/opt_41.c:#define RRTYPE_OPT_ATTRIBUTES (DNS_RDATATYPEATTR_SINGLETON | \
lib/dns/rdata/generic/soa_6.c:#define RRTYPE_SOA_ATTRIBUTES (DNS_RDATATYPEATTR_SINGLETON)
% 

Mark

-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org