1

Hi all,

We have a client who has run out of IP Addresses,

Scope - 10.0.0.1 - 10.0.0.254

Sub: 255.255.255.0

I know i can put them on a sub of 255.255.254.0 to give them 510 IP Addresses,

Is this a case of deleting the scope and creating a new scope with that subnet?

I am guessing i will have to re-enter any exclusions back in and also anything with a static IP address i will need to change the subnet as well,

Or am i missing something else?

Thanks in advanced

Karl

4 Spice ups
2

You can add another scope adjacent to the existing one. Might be a good time to set up a failover DHCP server with the new scope on it.

3

Just update the subnet mask for the exisitng scope and add a new scope in the new range with correct subnet. As you already know you will need to update static decvices first. I

d update those before making DHCP changes.

4

Thanks for the update Rockn and Alex,

Rockn, what is the best way of doing this,

Alex, how do I update the subnet mask on the existing scope? I thought this would be the easy way but I cant find away of doing this without deleting the existing scope.

5

You’re right can’t edit it in the GUI it seems. You could I suppose export the Scope and then edit the export and import it back in though using netsh Netsh utility to export and import DHCP scopes - Windows Server | Microsoft Learn

1 Spice up
6

It doesn’t let you modify the subnet mask on the fly.

I extended a scope recently and for the life of me I can’t remember if I found a workaround or just recreated it.

7

I have done this a few times, here is the article I had used to do this work.

Let us know if you have any issues with this.

2 Spice ups
8

Hi Phatam-snp,

This looks a lot easier then deleting and recreated it all,

I will be doing this next week on a server 2012, im guessing this will workout any problems?

9

The last time I did this in the middle of the day without issues. I changed the subnet mask on all of my switches, router, statically set devices (servers, printers) before I changed the DHCP scope. Everything can still talk to each other with the temporarily mismatched subnet mask as long as nothing is using an address in the newly expanded area. I saved changing my DHCP server for last. If you choose to do this during working hours, the only disruption would be is if any of your devices require a restart for the change. None of mine did.

3 Spice ups
10

Phatam-snp,

I have just tested this on a test server,

recreated the same scope as the client just added a random exclusion so all 10.0.0.*** was in use to see if it picked up the new ip address range.

Worked like a charm,

Laptop picking up 10.0.1.1 address can ping the server etc so all looks good,

Thanks for your help, not just Phatam-snp but everyone who had taken their time to reply,

I will let you know how I get on when we book this in with the customer.

11

I have done this on 2k8 boxes before as well as SBS (bleh). This is a great way to expand the scopes.

Also just like Da_Schmoo said, don’t forget to update all of the Networking hardware and Printers. otherwise you will be troubleshooting communication issues.

@karlthompson0674 @da-schmoo

12

That’s exactly what I suggested exporting the config using netsh then editing and reimporting it.

1 Spice up
13

So after a month of the client keep putting this off and off, they have finally agreed to do this tonight,

I will update you all how it goes,

Wish me luck ha ha

14

Thanks for all your help on this topic,

All went well yesterday and everything seems to be all working again today.

Success !!