DNS mess (home IP addresses on company network?)

[BJG]

I've recently started digging into the DNS setup on the network in my new(ish) workplace and wished I hadn't. It seems to be completely messed up.

 

For one thing, a lot of the entries in the Forward section are mismatched with the Reverse section. I've seen all the stuff about scavenging and clearing the cache etc., but it doesn't seem to fix this. I'm not sure how it got this way or how to sort it out. Can I somehow tell DNS to recalculate all the Reverse entries...?

 

(DNS isn't my forte. DHCP looks OK as far as I can tell, and the DNS settings in DHCP seem sensible. I'm not blown away that they've got two different DHCP servers on separate scopes that don't talk to each other, but that's another story. The two DHCP servers are also both DNS servers, but these are in sync. They're wrong, but at least they tally.)

 

Another weird thing that's happening is that laptops from remote workers are getting mapped to completely inappropriate IPs. Eg yesterday I found one staff laptop that showed up in DNS with a duplicate entry for the IP of one of the Hyper-V hosts, which is a bit concerning.

 

People take laptops home, which they can log into offline, or log into / connect to the VPN. The organisation has a 192.168.x.x address range, and I'm told that in the past they had a problem where IP addresses corresponding to users' home networks were getting registered in DNS, and this never seems to have been sorted out properly. From Googling I've found some discussion of the IPv4 client setting to "Register this connection's addresses in DNS", but I'm not sure if this is the root cause of the problem or how to fix it.

 

Things generally work (surprisingly), apart from the odd glitch, but it looks overdue for a fairly drastic overhaul. (The only problem I came across with the twin DHCP servers was that clients would abandon their reservations on one and defect to the other; I've now prevented this with MAC filtering. I'm aware of "split scope", which is probably what the person who set this up was attempting to do, and I need to revisit this sometime...but as I say, I think DHCP basically looks OK, but DNS seems quite messed up.)

 

(...oh, and the main DC/DHCP/DNS is on Windows 2012 Standard. The other one is on Windows 2012 R2. Lots to do, but one thing at a time...)

 

Help!?

 

*edit*

 

I see there are plenty of warnings to avoid 192.168.1.x/24 due to clashes with home networks for VPN users, which looks like part of the problem.

Edited May 12, 2022 by BJG

[BJG]

(...things are getting back under control now...)