what is difference between nslookup and ping?

[Guest]

We have first DC-a in city A, second DC-b in city B. Connection between them is 256K DDN. The question is, sometime, the client of city B can ping DC-a in city by name, while sometime can't even flush the dns cache. DC-a can always be pinged by ip address, and on client-b, nslookup can resolve the DC-a's name. Can anyone give me answer? Thanks.

 

[Herb Martin]

We have first DC-a in city A, second DC-b in city B. Connection between

them is 256K DDN. The question is, sometime, the client of city B can ping
DC-a in city by name, while sometime can't even flush the dns cache. DC-a
can always be pinged by ip address, and on client-b, nslookup can resolve
the DC-a's name. Can anyone give me answer? Thanks.

Besides the obvious (they do different things):

NSlookup bypasses the DNS client-side cache.

Ping uses the client-side DNS cache.

Of course they use different protocols so ICMP (ping) can be
blocked when DNS traffic is allowed (or vice versa) and some
servers might have ping responses disabled.

Even a DNS server might only accept such request on one of
multiple NICs.

 

[J.C. Hornbeck [MSFT]]

One thing you might try is adjusting the timeout for ping when you test
using the "-w" parameter. It may be the when you can't ping it's just
taking too long so it's timing out and reporting a failure. Also, when you
test with nslookup try each DNS that the client is configured to use. You
can switch servers using the "server" command at the nslookup prompt.

--
J.C. Hornbeck, MCSE
Microsoft Product Support

NOTE: Please reply to the newsgroup and not directly to me. This allows
others to add to and benefit from these threads and also helps to ensure a
more timely response. Thank you!

This posting is provided "AS IS" without warranty either expressed or
implied, including, but not limited to, the implied warranties of
merchantability or fitness for a particular purpose.

We have first DC-a in city A, second DC-b in city B. Connection between

them is 256K DDN. The question is, sometime, the client of city B can ping
DC-a in city by name, while sometime can't even flush the dns cache. DC-a
can always be pinged by ip address, and on client-b, nslookup can resolve
the DC-a's name. Can anyone give me answer? Thanks.

 

[Herb Martin]

One thing you might try is adjusting the timeout for ping when you test
using the "-w" parameter. It may be the when you can't ping it's just
taking too long so it's timing out and reporting a failure. Also, when you
test with nslookup try each DNS that the client is configured to use. You
can switch servers using the "server" command at the nslookup prompt.

Good point -- I made the mistake of "just answering the question."

Also, when ping fails try tracert to determine 'how far' the message
seems to travel.

 

[William Stacey [MVP]]

As a related note. I added a "ping" like feature to NetDig, which will
allow you to make "n" queries to your dns server in a ping like way. This
may or may not help you diag this particular issue, but could be handy for
your tool bag. Try it at www.mvptools.com.

--
William Stacey, MS MVP

We have first DC-a in city A, second DC-b in city B. Connection between

them is 256K DDN. The question is, sometime, the client of city B can ping
DC-a in city by name, while sometime can't even flush the dns cache. DC-a
can always be pinged by ip address, and on client-b, nslookup can resolve
the DC-a's name. Can anyone give me answer? Thanks.

 

[Guest]

Thanks all for the reply.

I don't think it is the time issue, because the time fixed to be about 40ms whether I can't ping FQDN name or not.
The DNS details are as below:
For zone, we have country zone, e.g. country.ms.com to stroe DC and server record. Primary country is stored on DC-a, Secondary on DC-b. For each city we have a city zone. e.g. cityb.country.ms.com. DC-b is delegateed to manage it, all workstastion in city b registered in this zone.
All the workstations in city B get DNS server address from DHCP server, the only one DNS server assigned in DHCP server is DC-b. Two DNS server are set in the forwarder on DC-b. one is DC-a and another is firewall(for Internet access).
Any idea?

----- J.C. Hornbeck [MSFT] wrote: -----

One thing you might try is adjusting the timeout for ping when you test
using the "-w" parameter. It may be the when you can't ping it's just
taking too long so it's timing out and reporting a failure. Also, when you
test with nslookup try each DNS that the client is configured to use. You
can switch servers using the "server" command at the nslookup prompt.

--
J.C. Hornbeck, MCSE
Microsoft Product Support

NOTE: Please reply to the newsgroup and not directly to me. This allows
others to add to and benefit from these threads and also helps to ensure a
more timely response. Thank you!

This posting is provided "AS IS" without warranty either expressed or
implied, including, but not limited to, the implied warranties of
merchantability or fitness for a particular purpose.

We have first DC-a in city A, second DC-b in city B. Connection between

them is 256K DDN. The question is, sometime, the client of city B can ping
DC-a in city by name, while sometime can't even flush the dns cache. DC-a
can always be pinged by ip address, and on client-b, nslookup can resolve
the DC-a's name. Can anyone give me answer? Thanks.