resolver's behavior

[Barry Margolin]

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
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