DHCP Failover Pools

[FN-GM]

Hi,

 

If you have setup DHCP Failover say 80% an 20% share. If the server with 80% of the pool goes down will the secondary server only handle 20% of the available addresses?

 

Why wouldn't you set this up as a 50 / 50 setup?

 

Thanks

 

[snagrat]

50% May not provide enough addresses. I thought the idea of 20% would be to ensure some users could work until the issue was resolved.

 

But this has all changed now as the is full DHCP failover in Server 2012 I believe?

[FN-GM]

50% May not provide enough addresses. I thought the idea of 20% would be to ensure some users could work until the issue was resolved.

 

But this has all changed now as the is full DHCP failover in Server 2012 I believe?

 

50% will be ok if you only use 50% of the scope?

 

DHCP failover replicates the leases between servers, so if the 80% server fails wouldn't the other server dish out the addresses they already have?

[plexer]

50% will be ok if you only use 50% of the scope?

 

DHCP failover replicates the leases between servers, so if the 80% server fails wouldn't the other server dish out the addresses they already have?

 

Not in a pre windows 2012 setup where you setup a split scope dhcp server.

 

If the 80% server fails over pre 2012 the 20% server can only allocate the addresses in it's pool and it knows nothing about the machines that already have leases.

 

2012 offers dhcp in load sharing or hot standby, in load sharing you can specify the amount of load to share but if 50/50 is picked then each server simultaneously offers an ip address, hot standby mode works are you'd expect.

 

Ben

[FN-GM]

So basically either way, If a server fails, everything DHCP wise will carry on as usual?

[Steve21]

So basically either way, If a server fails, everything DHCP wise will carry on as usual?

 

As long as it's configured for failover yes it'll just carry on working and end users shouldn't really notice anything. During our recently DR tests turn DC1 off and restart computer and it picks up DC3 response and it knows no different as long as it's set to failover etc

 

The 80/20 will just mean one DC is doing most the work normally, but 2012 wise it's standard 50/50 split as default.

 

Steve