DNS Issues after installing DameWare: Duplicate IP records, Can't get it to scavenge, Pings reply wrong IP, etc.

Eric Jack
Eric Jack used Ask the Experts™
Forgive the length, but I want to provide a detailed description of the problems I'm running into what I've checked so far:

I purchased Solarwinds DameWare to help with supporting PCs in-house. I started running into problems where it would not connect to some computers. Other computers worked fine. One of the error messages on DW said something along the lines of "The computer you're trying to connect to is actually a different computer. Do you want to continue?" So I started troubleshooting and running into some strange DNS weirdness.

Starting with the two computers involved with the error above, I pinged both by name from my PC and they both returned the same IP address. When I went to those PCs, one of them had that IP and the other had a different IP. Digging further, I started running into a few more computers that when pinged by name returned incorrect/duplicate IPs.

Some research indicated I might not have DNS scavenging turned on. Odd thing is, everything worked fine before installing DameWare. I was using UltraVNC for report desktop support, and now that won't connect to these problem PCs either. So I started checking my DNS settings on the Domain Controller. (I only have one DC and it is the only thing managing DNS that I am aware of.)

Logging into the Domain Controller > Server Manager > Tools > DNS
When I look in the tree under my server > Forward Lookup Zones > my domain, I'm seeing a list that includes records that are months or years out of date! And multiple entries that have the same IP!

I tried checking the settings: R-Click my domain in the tree > Properties > General tab > Aging button > checking the box and setting an interval in both fields (1 hour). But even after that time, there was no change to the DNS list.

Now, when I try pinging some addresses from my PC, I'm getting even stranger results: Whenever I try to ping anything that has a duplicate IP in that list, I get "Reply from Destination host unreachable", and the 18 address is the IP currently assigned to my PC.

I must be missing something simple.

I also don't understand why I was never having problems until I started using DameWare (local install only. I'm not using the DameWare server.)

Any assistance would be greatly appreciated!
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Top Expert 2014
I don't believe this has anything to do with DameWare.  Your situation is pretty typical when you've got clients that get dynamic IPs, particularly as they move back and forth between wired and wireless connections.  Here's a good blog entry on DNS scavenging that I reference often.
You'll want to avoid setting the refresh and no-refresh intervals too short, as you can end up with records that are unable to be updated and get scavenged.
Eric JackIT Manager


Well, going over that technet blog helps. When I decided to check DNS yesterday, that's when I noticed that scavenging wasn't turned on at the server or zone level. I turned it on and hoped for a quick refresh. Looks like i need to be patient... several weeks patient by the blog. I currently have the zone level set for 1 day (no refresh) and 7 days (refresh). At the server level, I put it at 7 days scavenging period. I don't see a setting for resource level other than a checkbox to allow it to be scavenged.

But I'm still a little confused.

1. Some of these super-outdated resources should be able to be scavenged right away, right? Looking at one, the record timestamp is 12/7/2015! However, the TTL seems to be stuck at 15 minutes.

2. One of the problem computers (DT-MAROOM) shows up once in the records. It has the incorrect IP listed. The timestamp is 12/9/2016, yet the computer is turned on, so shouldn't it have updated the timestamp? The TTL on this PC is stuck at 20 minutes. I don't see a second entry for DT-MAROOM with the correct IP, so if I manually deleted it, it would bugger things up since it would be missing.

3. I'm not a patient person. Plus the fact that this is hampering my ability to connect to computers in the building for support. Is there a way to expedite this process without buggering things up? Can I force faster updates and scavenging? Can I manually delete and add the correct record?
Top Expert 2014
There's a whole interaction between dynamic DNS update, zone settings, DHCP settings, and DNS scavenging, and it can get convoluted very fast.

1.  Yes, they should be able to scavenged now.  The TTL isn't involved here.
2.  One scenario could be that the security of the record isn't allowing it to be updated by the machine.  It's not going to mess anything up if you delete an incorrect record.  After deleting the record, you could run ipconfig /registerdns on the machine for it to try registering the record without waiting.
3.  Yes, you can delete the incorrect records as mentioned above.  And I wouldn't be at all surprised that you do have to do this for some records anyway.  I would recommend only doing that for high priority items.  You need to take the time and understand what is happening and make sure that things are working correctly, so that you don't end up with empty zones.  The way I would approach it is to follow the article (yes, it does take patience), and once you know it's working then you can go about reducing the refresh and no-refresh intervals and scavenging period, safe in the knowledge that you know what effect the changes will have.

BTW, another article that describes more on DHCP settings to help keep your network DNS records clean.
Eric JackIT Manager


Setting up DNS scavenging seemed to do the trick. A week later, after the scavenging has had a chance to do its thing, and the DNS records in the DNS Manager on the domain controller are much cleaner! And most duplicate IPs in the records are gone (there's still a couple...)

With the duplicate and incorrect IPs gone from DNS Manager, DameWare should work much better now.

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