network error during host resolution (exchange error)

[Kelly]

Seems like every so often I get this problem. A reboot
of the DNS server takes care of it for a while. But then
it shows up again. Thanks for the advice.

Z:\>nslookup
Default Server: mtadams.comsyspdx.com
Address: 192.168.2.2

set d2
set type=mx
yahoo.com

Server: mtadams.comsyspdx.com
Address: 192.168.2.2

------------
SendRequest(), len 41
HEADER:
opcode = QUERY, id = 2, rcode = NOERROR
header flags: query, want recursion
questions = 1, answers = 0, authority records =
0, additional = 0

QUESTIONS:
yahoo.com.comsyspdx.com, type = MX, class = IN

------------
------------
Got answer (112 bytes):
HEADER:
opcode = QUERY, id = 2, rcode = NXDOMAIN
header flags: response, auth. answer, want
recursion, recursion avail.
questions = 1, answers = 0, authority records =
1, additional = 0

QUESTIONS:
yahoo.com.comsyspdx.com, type = MX, class = IN
AUTHORITY RECORDS:
-> comsyspdx.com
type = SOA, class = IN, dlen = 46
ttl = 3600 (1 hour)
primary name server = mtadams.comsyspdx.com
responsible mail addr =
administrator.comsyspdx.com
serial = 1821
refresh = 900 (15 mins)
retry = 600 (10 mins)
expire = 86400 (1 day)
default TTL = 900 (15 mins)

------------
------------
SendRequest(), len 27
HEADER:
opcode = QUERY, id = 3, rcode = NOERROR
header flags: query, want recursion
questions = 1, answers = 0, authority records =
0, additional = 0

QUESTIONS:
yahoo.com, type = MX, class = IN

------------
DNS request timed out.
timeout was 2 seconds.
timeout (2 secs)
SendRequest failed
*** Request to mtadams.comsyspdx.com timed-out

 

[Jonathan de Boyne Pollard]

K> Thanks for the advice.

Here are three pieces, then:

1. Don't use "nslookup". Several better DNS query tools are widely
available. Use them. The fact that the search list processing that
"nslookup" is doing is obfuscating what is happening here is a good example of
the problems for DNS diagnosis that the flaws in "nslookup" cause.

2. Get into the habit of supplying fully qualified domain names to your
diagnostic tools when performing DNS diagnosis, rather than supplying
unqualified names are you are doing.

3. Check that the DNS server listening on 192.168.2.2 actually provides proxy
DNS service in the first place. Does it have IP connectivity (via another IP
address of course) to the rest of Internet so that it can perform query
resolution itself ? Is it configured to forward queries to another proxy DNS
server ? (If so, make these same checks against that server as well.) Is
recursion even enabled at all ?