resolver's behavior
Barry Margolin
barmar at alum.mit.edu
Fri Apr 21 00:27:30 UTC 2006
In article <e2964j$2u9e$1 at sf1.isc.org>,
Kevin Darcy <kcd at daimlerchrysler.com> wrote:
> Frank Y.F. Luo wrote:
>
> >I am a little confused about a resolver's behavior, like ping command,
> >nslookup command,
> >
> >I am querying against a DNS server with recursive turned off
> >
> >#dig www.slashdot.com
> >
> >; <<>> DiG 9.2.4 <<>> www.slashdot.com
> >;; global options: printcmd
> >;; Got answer:
> >;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 1794
> >;; flags: qr rd; QUERY: 1, ANSWER: 0, AUTHORITY: 13, ADDITIONAL: 0
....
> Command-line tools like "ping" typically use the "system" resolver,
> which is usually configurable (via a system config file like
> /etc/nsswitch.conf or the like) and may or may not even include DNS as
> one of its sources of name information. If the system resolver does look
> at DNS at all, it'll do so by generating recursive rather than
> non-recursive queries. So for a valid comparison to what "ping" is
> seeing, you should do recursive rather than non-recursive queries.
He did. Don't you see "rd" (Recursion Desired) in the "flags:" field?
It's the server that has recursion disabled (hence the missing "ra"
flag), not the client.
--
Barry Margolin, barmar at alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***
*** PLEASE don't copy me on replies, I'll read them in the group ***
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