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canuckconsulting
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DNS Issue - incorrect IP shown for host

We have a situation where one of our Windows 2012 servers (SERVER_A) had the wrong address for another Windows 2012 server (SERVER_B).  It was wildly wrong with the leading octet being wrong.  The DNS server was reporting the correct address for SERVER_B and, after flushing DNS SERVER_A is now fine.

My question is how could this happen?  I've checked the hosts file on SERVER_A and nothing relevant there.



DNS Issue
Windows Server 2012DNSWindows Networking

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canuckconsulting

8/22/2022 - Mon
bbao

when it reports incorrectly again, run IPCONFIG /DISPLAYDNS to how the incorrect IP was resolved and cached.

BTW, did you try a reverse check against the incorrect IP ever reported? was its domain name related to your business?
canuckconsulting

ASKER
Following your advice, that ip address is the DNS server for the hosting company our virtual server is located on.  Now below I logged back on to SERVER_A and tested the connection to it's DC, verifying it is set correctly to BBCDC07.  The IP address shows correctly via DNS but when I ping it I get the same ip address i was getting in my first post.  Something very screwy is going on but I'm unsure how to dig deeper.

bbcdc07.png
Here's the results of the DisplayDNS you mentioned:

DisplayDNS
yo_bee

Have you tried to flush the DNS cache on the server that is not resolving the correct ip

[code]ipaddress /flushdns[/code]
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canuckconsulting

ASKER
Yes, that was the third command shown in my first post.  As noted, it resolved the first issue but not the issue shown in my previous post.
yo_bee

You mentions a VM in your question. How many NIC adapters are on that server? And are all of the reporting back to your DNS server.

Also is the ip you are see one from your ISP?
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bbao

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canuckconsulting

ASKER
yo_bee - On both the DC and the client machine I only see a single network adapter as below:

Adapter

Bing CISM / CISSP - Thanks for the info and I'm very embarrassed to have botched my masking!

Pinging an unknown host results in "could not find host" as shown below.  I think this behaviour is correct.

Ping unknown host
How did you perform the DNS health check?  Unfortunately I have limited experience with DNS so am struggling with the basics.  If i could reproduce your health check perhaps I could interpret and highlight the issues with management to justify getting some external help.
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Aard Vark

Do you use WINS? Ping will use the result returned from local cache if cached or from your WINS/DNS servers. Whichever service replies quicker wins. Is the server multi homed (has multiple NIC's)? If it is, make sure only the IP you want registering an address is set to register its record in DNS.
canuckconsulting

ASKER
DrDave242 - Yes, our internal AD domain is named  bb*****td.com.  Your conclusion re an external DNS being unsuccessfully queried for an internal address makes sense to me but I don't see how it happened.  Below shows the four DNS servers configured on SERVER_A.  The last two DNS servers are unaware of local addresses but time out instead of return the 12.x.x.161.  
DNS Servers
Learnctx - No, WINS is not configured and we only have one nic on SERVER_A.

WINS
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canuckconsulting

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Thanks for the help guys; I hope the point distribution is fair.
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