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Computer is pinging. When I nslookup by hostname, it is missing. When I RDP using hostname, it resolves to another server name. How to fix?

Question

Friday, January 15, 2016 11:16 PM

Hi,

When I ping this computer name (ex. SERVER A) it pings.  When I nslookup SERVER A, it is missing.  When I nslookup the IP Address, it resolves to another name (ex. SERVER B).  When I RDP to SERVER A, it resolves to SERVER B.

I looked at both forward and reverse DNS entries for SERVER A but I couldn't find SERVER A. I sort by IP ADDRESS and all points to SERVER B.

How do I fix this? SERVER A is not a valid server. SERVER B is the real live server.

Pls. advise.  Thank you!

All replies (19)

Wednesday, January 27, 2016 8:22 AM ✅Answered | 1 vote

Hi SwissMiss,

>>However if I ping from any workstations (which is on a different subnet from our Servers), it is resolving to SERVER B.

Disable NetBios over TCP/Ip and try again.

Best Regards,

Leo

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Monday, January 18, 2016 6:41 AM

Hi SwissMiss123,

When a Client starts a Name Query Resolution process, it will query according to the following order:Local Cache(with HOSTS file loaded first) èLocal DNS server

According to your description,  there is no records in the DNS server for SERVER A, the IP ADDRESS is just associates with SERVER B.

So please check the HOSTS file and Local Cache at first.

You could use “ipconfig /flushdns” to clear the Local Cache. And the HOSTs file is typically stored in the %SYSTEMROOT%\System32\etc.

Make sure there is no record for SERVER A in that two place, then try again.

Best Regards,

Leo

                     

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Tuesday, January 19, 2016 4:36 PM

Thanks Leo for the reply.  Here's what's weird...

- SERVER A doesn't exist. It used to be an old machine but that machine has been deleted long time ago.  So there's no hostfile to check.

- SERVER B is a newly configured Windows 2012 virtual machine.  So the Hostfile is clean.  I also double check and the host file has no other entries.

But I still did flushdns (just in case my machine is holding some cache) and SERVER A is still pinging with the IP address of SERVER B.

I don't know how this is possible with SERVER A.

Thank you!  Anyone?

Wednesday, January 20, 2016 5:01 AM

Hi SwissMiss123,

Check the client’s cache and Hosts file, not the server’s.

You used SERVER A for old machine, it would be cached by clients, or Hosts file on client has been changed before.

Best Regards,

Leo

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Wednesday, January 20, 2016 5:14 PM

Thanks so much Leo!

I ping from random Windows 7 computers and it is pinging back. But if I ping from my servers (both Windows 08 and Windows 2012) it doesn't return any result from ping (appears offline).

There's nothing on my Win 7 computer hostfile that specifies SERVER A.  I looked high and lows on my DNS entries, hostname, alias, reverse and forward, I found nothing that shows SERVER A or the Ip address pointing to SERVER A - but it still pings from my workstations.

I even ipconfig /displaydns but I didn't see any entry of SERVER A there. I saw bunch of other entries but not SERVER A.  I still did ipconfig /flushdns to clear whatever entries are there and it works.  But it is irrelevant because SERVER A is not on that list anyway.

What else could it be that my Win 7 computers is pinging to it? Thanks again.

Wednesday, January 20, 2016 5:31 PM

Just as an idea - do you have WINS services configured on your network?

Wednesday, January 20, 2016 5:36 PM

No. We don't use WINS. Only DNS. Thanks for checking!

Wednesday, January 20, 2016 5:40 PM

Ok, so the clients are resolving server A to the IP of server B. If server A does not exist, why are you trying to ping/connect to it? Why not just keep connecting to server B?

Ultimately......what is the actual problem??? You describe an interesting resolution glitch, but what is it that is not working?

PS: Did you check the local lmhosts file on the clients? Perhaps it's resolving using NetBIOS resolution instead of DNS?

Wednesday, January 20, 2016 5:52 PM

Hi MikeeMiracle,

"Ok, so the clients are resolving server A to the IP of server B. If server A does not exist, why are you trying to ping/connect to it? Why not just keep connecting to server B?"

- Yes, clients are resolving server A to the IP of server B. 

- Yes, server A does not exist. 

- It's not that I was trying to connect or ping to Server A.  I discovered it by accident when I was inventory/identifying which server names are live, valid and whatnot.  We also repurpose names sometimes. 

It's just for accuracy.  One day we may end up needing to re-use Server A's hostname but I need to straighten this out.  I just can't leave it like this.

I have no problem connecting to Server B and all is well with that.  But, I need to resolve this issue as it may pose a problem (that we haven't discovered yet.. who knows).  It appears to me that the clients DNS is not correct or accurate and that is a problem.

Thursday, January 21, 2016 2:32 AM

Hi SwissMiss123,

MikeeMiracle mentioned Netbios, have you checked yet?

Clear the cache on DNS server. (DNS manager>Right click on DNS server>Clear cache)

You could add a host record in DNS for SERVER A, with another IP address. Then  PING and  NSLOOKUP SERVER A and SERVER B. If the result is correct, delete the record you just added, flush DNS cache on client and try again.

Best Regards,

Leo

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Thursday, January 21, 2016 2:29 PM

Ok, so it does not sound like a DNS resolution, which would have an entry in the local hosts file or in the DNS server. It might still be a NetBIOS issue, check your lmhosts file on the local machine having the resolution issue, or check to see if you have WINS configured on the domain controller, WINS was used in Windows as the promary method of name resolution prior to Windows 2000 / Active Directory. It may still exist if you have any legacy application that require it.

If it's not in local hosts or lmhosts file, and not the in the server in DNS or WINS.....

..then when you try and ping server A, the client will braodcast out to your network asking if any machines have this name, at that point a certain machine who believes it is called server A would respond.

From what you have said so far, I would say almost certainly that you have an enrty for it within your local lmhosts file. The lmhosts file does the same thing as the hosts file except for NetBIOS names instead of DNS names.

Thursday, January 21, 2016 6:29 PM

Hi Leo,

I did all your suggestions here and this is what happened:

When I created a host entry of Server A and pinged it, it timed out.  This makes sense because Server A doesn't exist.

But when I deleted it again (with the DNS clear cache actions in between), it goes back to resolving to Server B. 

So, without a host entry, it pings back to Server B.

Hi MikeeMiracle,

We don't use WINS for many many years. So that's out.  I looked at my lmhost and it's a clean lmhost file. We don't touch hostfile or lmhost file on our staff computers so I would rule that out.  But just for my sanity check, I checked my host and lmhost files, nothing special there.  I tried pinging from other Windows 7 computers and it pings to Server B.  So this doesn't only happen on my workstations but other workstations too.

Friday, January 22, 2016 12:11 AM

Name resolution is either happening locally on the client machine (cache, hosts file, or lmhosts file), or over the network (DNS, WINS, NetBIOS, LLMNR). Assuming the name Server_A is being resolved over the network, and with all of the troubleshooting steps you've tried, the best thing to do would be to just open a network capture analyzer and check the traffic.  That will at least tell you the exact source of the name resolution.

You could also check:  Is the client machine on the same subnet as the IP address that's resolved when you ping Server_A?  If so, it could be from a NetBIOS or LLMNR response.  What if you ping the FQDN of Server_A?  Does it still resolve?

Monday, January 25, 2016 5:18 PM

Thanks Ryan.  Based on what you said, I noticed that it is NOT pinging when I try to do it from another computer of the same subnet.  Instead, it pings only when I do it from a computer with different subnet (mainly workstations).  If I ping from another server that has the same subnet at Server A, it does not ping.

Aside from the network capture analyzer... what do you think?

Tuesday, January 26, 2016 5:20 AM

Try below steps:

1. Delete if you have any static DNS record for that IP address in DNS server.

2. It looks you have static PTR record..check in the reverse lookp zone and delete that record.

3. Try to do remove the server from the domain and rejoin to the domain.

Click propose as answer if it helps.

Tuesday, January 26, 2016 5:44 PM

Hi Sam_In,

Thanks for your suggestions but...

1.  I have no static DNS record of SERVER_A.  SERVER A doesn't exist.  Therefore I have nothing to delete.

2.  Nothing exists on the PTR record also.  I checked all our DNS servers both forward and reverse.  No SERVER A entry.

3.  I cannot remove SERVER A or join/rejoin.  The server doesn't exist.  Secondly,  SERVER B (where SERVER A is resolving to when pinging) is a live server I cannot remove from the domain or rejoin.  SERVER B is in production.  There's no way I am removing or rejoining this.

Note that if I ping from another subnet, SERVER A times out (Ex.  if I ping from another server because all our servers are on a different subnet than our workstations).  However if I ping from any workstations (which is on a different subnet from our Servers), it is resolving to SERVER B.

Wednesday, January 27, 2016 4:33 PM

Thanks Leo! That was it! Thank you!

Before I mark your reply as the answer, I have couple of questions:

1.  Ours was set to the Default setting " Use NetBIOS setting from the DHCP server...". Is that wrong? Do you suggest that I change our Group Policy to disable the the NetBIOS setting to receive a more accurate ping? 

2.  What ramification are we facing if I disable that to everyone?  We don't use WINS.  We only use Windows 7, Server 2008 and Server 2012.  It looks like disabling it should be fine but what do you think? https://technet.microsoft.com/en-us/library/cc940063.aspx

Thursday, January 28, 2016 5:28 AM | 1 vote

Hi SwissMiss123,

1. Considering the issue and you have internal DNS server, you could disable it.

2. Since you have internal DNS server and fuctioning well, there would not be any effect as far as I know.

Best Regards,

Leo

Please remember to mark the replies as answers if they help and unmark them if they provide no help. If you have feedback for TechNet Support, contact [email protected].

Thursday, January 28, 2016 4:22 PM

Thank you very much!