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DNS - nslookup fails to identify server

By techrepublic@winandware ·
I have a 1.5Mbps cable modem connection with two static IP addresses. I've configured two Windows 2000 Servers with AD-integrated DNS. I've performed local nslookup queries on both servers and everything seems just fine -- including reverse lookups.All of th PC's on my LAN are using the new DNS servers to successfully resolve Internet names. But when I attempt to perform an nslookup using any *remote* DNS server, the reverse lookup always fails. I've ensured that my firewall isn't blocking port 53 TCP/UDP. Is it possible/likely that my provider is blocking port 53 to my IP addresses somehow? Any clues or insight would be greatly appreciated! I would really like to get this problem identified as quickly as possible. Thank you!

Archer
Archer

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DNS - nslookup fails to identify server

by kahana In reply to DNS - nslookup fails to i ...

HI ,
several questions that might clarify :
Are you using nat for the dns servers or they using legal ip addresses ?
if your cable modem or firewall are using nat than the dns is being filtered and reverse will not work.
if you are using legal addresses then I would try to pull the zone from one of the remote servers and see if it gets thru ,
Is your zone is updated to your isp.
Who is the Primary and secondary dns for the zone?

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DNS - nslookup fails to identify server

Thanks for your interest. As I stated, I have two static IP's that were issued to me by my ISP. One address is assigned to each of my servers.

Unfortunately, I'm very unclear about the rest of your message. I'm not using my ISP's DNS servers in any way at the moment. One server is providing ICS on the network, but that should not be affected by the firewall in any way. If you can clarify your suggestions/questions a bit more, I'll do my best to answer. Thanks!

Archer

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DNS - nslookup fails to identify server

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DNS - nslookup fails to identify server

Point value changed by question poster.

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DNS - nslookup fails to identify server

by vh_s In reply to DNS - nslookup fails to i ...

Unclear to me what you define with *remote* dns. Is this your ISP dns server ?

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DNS - nslookup fails to identify server

by Shanghai Sam In reply to DNS - nslookup fails to i ...

By "remote" DNS server, I meant any DNS server from outside of my existing network (which would be considered "local").

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DNS - nslookup fails to identify server

by Sergey Kovzik In reply to DNS - nslookup fails to i ...

Reverse DNS is provided by your ISP, if it holds class C network. It is possible to delegate this to you, but this needs some configuration on your ISP.

Sincerely, Sergey
Brainbench MVP for Win98 Administration

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DNS - nslookup fails to identify server

by Shanghai Sam In reply to DNS - nslookup fails to i ...

Having received no timely responses that were useful, I proceeded to collocate my server two weeks ago. This resolved the problem, which may very well have been a result of my ISP providing reverse DNS, as you suggested. I do appreciate your effort to assist, and I regret my oversight of not closing this issue sooner. I've been a bit busy. Take care.

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DNS - nslookup fails to identify server

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