How Do You Set Up Windows DHCP Failover

siringo

@scottalanmiller said in What Are You Doing Right Now:

@siringo said in What Are You Doing Right Now:

I have dhcp running on 2 servers with non overlapping address scopes
server 1 hands out a.b.c.100 - 254
server 2 hands out a.b.d.100 - 254

So to go along with your question. This means each server has 155 addresses to hand out and there are 310 addresses in the pools.

With the way it is set up, only 155 addresses are guaranteed to be usable. But if you made the scope continuous not only would you get both sets, but you'd get c.100-254, but c.100-d.254 for 410 total addresses! Way more. Because you have loads being lost just because you are blocking off random addresses in the middle of your range, too.

yep, no worries, thanks. but how can i add a second dhcp server for redundancy?

scottalanmiller

@siringo said in What Are You Doing Right Now:

@scottalanmiller said in What Are You Doing Right Now:

@siringo said in What Are You Doing Right Now:

I have dhcp running on 2 servers with non overlapping address scopes
server 1 hands out a.b.c.100 - 254
server 2 hands out a.b.d.100 - 254

So to go along with your question. This means each server has 155 addresses to hand out and there are 310 addresses in the pools.

With the way it is set up, only 155 addresses are guaranteed to be usable. But if you made the scope continuous not only would you get both sets, but you'd get c.100-254, but c.100-d.254 for 410 total addresses! Way more. Because you have loads being lost just because you are blocking off random addresses in the middle of your range, too.

yep, no worries, thanks. but how can i add a second dhcp server for redundancy?

Well first, almost no one needs one. That's not generally a real world problem. DHCP is crazy reliable, and there are all kinds of mechanisms to make DHCP resilient to downtime.

That said, obviously cases exist where you need redundancy. This is done through DHCP HA. Basically in your DHCP console, you just select "Configure Failover" and it walks you through the process.

https://www.itprotoday.com/windows-78/configuring-dhcp-failover-windows-server-2016

scottalanmiller

This guide might be better.

http://techgenix.com/high-availability-dhcp-server/

dbeato

Official Guide here for Server 2012 R2 But should be the same process
https://docs.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2012-r2-and-2012/hh831385(v%3Dws.11)
You also need to setup a Failover Cluster for this as well
https://www.dell.com/support/article/hk/en/hkbsd1/sln312477/how-to-configure-dhcp-failover-cluster-on-windows-server-2012?lang=en