CNAME of a DOMAIN name returns sometimes the soa and sometimes nothing, Why?

[Mathias Koerber]

-----Original Message-----
From: news.csnet.nl <renez at csnet.nl>
Newsgroups: comp.protocols.dns.bind
To: comp-protocols-dns-bind at uunet.uu.net
<comp-protocols-dns-bind at uunet.uu.net>
Date: Friday, June 25, 1999 1:40 AM
Subject: CNAME of a DOMAIN name returns sometimes the soa and sometimes
nothing, Why?


|My problem is that a domain i-55.com cannot send email to my domain
csnet.nl
|the response is nameserver time out.
|I believe the nameserver for the i-55.com isn't setup right because if I
ask
|it something about i-55.com it claims not to be authoritive for that zone.
|How ever that might be a side issue.
|
|The mail software does a check for a the cname of i-55.com this doesn't
|succeed and that gives a nameserver timeout.
|why does a lookup for a  CNAME of a DOMAIN name returns sometimes the soa
|and sometimes nothing?

It doesn't. In your first example there was no reply because of a SERVFAIL
error,
in the second there was no reply (necause no such record existed), but
addition data was returned in the AUTHORITY section.

see below.

|
|e.g. dig  i-55.com cname  versus dig redhat.com cname
|
|
|--------------------------i-55.com------------------------
|; <<>> DiG 8.2 <<>> i-55.com cname
|;; res options: init recurs defnam dnsrch
|;; got answer:
|;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 6
|;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0
|;; QUERY SECTION:
|;;      i-55.com, type = CNAME, class = IN

status: SERVFAIL:. No ANSWER, AUTHORITY OR ADDITIONAL sections returned.

|
|----------------redhat.com--------------------------
|; <<>> DiG 8.2 <<>> redhat.com cname
|;; res options: init recurs defnam dnsrch
|;; got answer:
|;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 6
|;; flags: qr aa rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0
|;; QUERY SECTION:
|;;      redhat.com, type = CNAME, class = IN
|
|;; AUTHORITY SECTION:
|redhat.com.             1H IN SOA       ns.redhat.com. noc.redhat.com. (
|                                        1999062200      ; serial
|                                        1H              ; refresh
|                                        30M             ; retry
|                                        1W              ; expiry
|                                        1H )            ; minimum
|


status: NOERROR

But:  ANSWER: 0 (ie there is no CNAME for redhat.com but there may be other
records for redhat.com).
Flags: aa (ie the nameserver you queries answered authoritatively, because
it is
authoritative for the domain redhat.com, or because it had just fetched a
reply from
an authoritative nameserver for the first time)

As there are no ANSWERS to you question (for a CNAME for redhat.com), there
is no
ANSWER section.
named however additionally return the AUTHORITY section telling you about
the
AUTHORITY of the domain. In most cases the AUTHORITY section may contain
NS records pointing to the authoritative nameservers for the domain, so that
you can
check there.

It might possibly also return an ADDITIONAL section which might contain A
records
for any records in the ANSWER and AUTHORITY section (if known by the
replying
nameserver) to spare you a lookup before you use those records.

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