How to Change the Subnet Mask on a Domain Controller?
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TechyTurtle89
I need to change the subnet mask on our primary domain controller as we're moving from a /24 to a /22 subnet in January. The IP address and gateway will stay the same, so it's just the mask that's changing. The networking team will manage the router and VLAN adjustments, and we plan to create a new DHCP scope while migrating existing leases and reservations. We'll also update our Active Directory sites and services to reflect the new mask. Is there anything crucial that I might be missing? Any advice would be greatly appreciated!
Answers
Also, make sure to update the range in your sites and services. You could do it ahead of time to make the transition smoother.
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Don't forget to ensure your PTR DNS zones cover the entire new range! That way you won't run into any issues later on. Just keeping it comprehensive is key.
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Your plan sounds solid, but having 1000 servers in the same subnet is unusual. It might make sense to investigate having a VLAN for your servers instead. It could make management easier in the long run.
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You've got much of it covered, but here are a few additional things to confirm before and after the switch:
- Perform a static IP audit. Make sure there aren’t any hosts still assigned statically with a /24 mask, as this could cause routing problems.
- Check your firewall and security rules because any old ACLs might block traffic after the mask change.
- Be mindful of monitoring and backup tools since their discovery ranges often depend on subnet definitions.
- For reverse DNS, if the new /22 spans into additional class C space, you'll want to ensure the zones and scavenging settings are accurate.
- Remember, for any other domain controllers, you should force DNS re-registration after the change to ensure records are updated properly.
TechyTurtle89: These are fantastic tips! Thanks for the insights!
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Don’t forget about devices with static IPs like printers, scanners, and storage devices. It’s crucial, especially if the gateway is changing.
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TechyTurtle89: Thanks for the reminder! We actually have the PTR DNS zones set up, but I appreciate you bringing it up!