Hi Guys
Kevin Darcy
kcd at daimlerchrysler.com
Wed May 26 22:12:29 UTC 2004
Servet Zeybek wrote:
>I got confused with query types CNAME and SOA! lets assume that im sending a
>CNAME request my name server for abc.com. What if theres no alias assaigned
>to this name and it is in fact the original name. I receive an authoritative
>answer in this case!
>
If you send a CNAME query for a name, and the name exists but owns no
CNAME record, you should get a normal (NOERROR) response with 0 answers.
Whether the response is authoritative or not will depend on whether it
was answered from cached data.
does that mean if theres no alias, we receive the
authoritative name server for our request!
I don't quite understand the question. Are you talking about a referral?
You might get a referral if you send a non-recursive query, or the
server declines to honor your recursion request, and the server doesn't
happen to have the exact answer in its cache.
>Second, what does this SOA(start of a zone of authority) really mean!
>
The name is confusing. Just think of an SOA record as a kind of
"super-record" that defines certain parameters for a whole zone,
including master/slave replication parameters, and negative caching
information.
>again,
>if i send a request (abc.com) and receive an answer, is this the
>first(start) name server for the zone i requested!!what does it really mean
>to get the start of a zone of authority???
>
You can get an SOA record a) in the Answer Section if you queried for an
SOA in the first place (i.e. you set your query type to SOA or to "*"
aka "ANY") or b) in the Authority Section along with a response code of
NXDOMAIN, if the name you asked for doesn't exist. In the latter case,
the function of the SOA record is to serve as a "negative caching
record", i.e. to tell the requestor how long to remember the fact that
the name doesn't exist.
- Kevin
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