I'm working on migrating our DHCP servers, and we've always encountered issues related to DHCP—especially with DNS records going wrong. I'm curious if anyone has experience with hot-standby failover setups. Did it go smoothly for you? We're considering disabling DNS scraping before we start the migration. Any advice or experiences would be appreciated!
8 Answers
A lot of DNS issues can stem from cache problems. Every DNS record has a time to live (TTL), which could be causing those long delays if the MINIMUM value in the SOA record is high. Fixing these often involves controlling which DNS servers clients use to clear out old cache. Knowing how to query and troubleshoot with tools like nslookup or dig is super important!
Definitely let the remaining server know when one goes down instead of just waiting it out. Proving your failover strategy is crucial before production deployment. Also, always back up! That’s how I’ve successfully replatformed domain controllers before.
Don't forget to learn how to back up your databases and services before starting any migration!
Setting up Load Balanced DHCP is pretty straightforward post-Windows 2016. Most work goes into ensuring your routers have the right forwarders. This method is distinct from Split Scope or Failover.
I haven't done hot standby, but I've worked with active/active configurations and they work great. You can split the load 50/50 across subnets—just keep in mind that the primary server responds instantly, while the secondary has about a 2-second delay. I wouldn’t change how I’ve set it up; it’s been super reliable for us!
I wanted to go active/active too, but management insisted on hot standby because they think active/active uses too many IPs. What has been your experience?
For a smooth transition, I'd recommend exporting your settings, importing them to the new server, setting your new server scopes to active, and then making the old ones inactive. Don’t forget to update your Helper IPs and you should be good to go!
This is the way.
Just a heads up, if you adjust the scopes or options later, you'll need to sync them manually.
Yes, I’ve set up hot standby DHCP in testing and it has worked well, but I haven't implemented it in production yet. Just remember to adjust your IP helper settings on the switches!
Thanks for the tip, already confirmed with the network team!
Why did you choose hot standby over active/active?
This is the way!