strace -v -o filename host myserver.example.com
Regards
strace -fvvvto filename -s 2048 <cmd>
is my usual form of calling strace when I don't know what I want from
strace. I think you want to add a -f to follow any forked processes at
the least.
When I set up a bogus nameserver in my resolv.conf and strace it, I see
resolv.conf get read and then I see a
sendmsg(20, {msg_name(16)={sa_family=AF_INET, sin_port=htons(53),
sin_addr=inet_addr("192.168.1.2") ...
and then later, I see a few -1 EAGAIN Resource temporarily unavailable.
Next I see it attempt a sendmsg to the next IP in the list which gives
it an answer in a recvmsg a few lines down.
If I put a correct nameserver back in resolv.conf and redo the strace, I
only see it attempt the first.
So, a shortened version of strace that would just track the sendmsg call
would be
strace -f -e sendmsg -s 2048 host myserver.example.com
If I don't do it with the -f flag, then I don't see the query process
happening.
Hugh
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