IP reservations - Advice

[Edu-IT]

I need to reserve a bunch of IP addresses (.10, .11, .12 etc) which according to DHCP have already been activated. What would be the best way for me to get 20 odd IP addresses back? We have a 10.56.117.x and 10.56.118.x range so there's enough places for me to grab the IP addresses from here rather than create another range such as 10.56.119.x.

 

If I add in reservations when the address is already in use then there will be conflicts?

[mrmontymick]

No, just add in the reservations but don't use them until the active lease expires on the DHCP.

 

Once the active lease expires the DHCP server will issue them with another IP address and you can start using your reservations.

[SYNACK]

Just add in some exclusions to the address pool covering the addresses you want and wait a while, if your lease period is not to long when the client lease of the IP expires it will ask for another and the server will allocate it one from the pool that is not excluded. You can then add your reservations with no conflict issues, this is probably the safest way of going about it. You can also just add the exclusions then use psexec or something to make the clients refresh their IPs instantly.

 

You can probably just add the reservations as the DHCP server should check that it is not allocated before handing it out but this may either delay the handout of the assigned reserved address or cause a conflict depending on your server setup.

[sted]

you can create a block of ips the server wont dish out that will clear them out as pcs request new addresses then create the reservations as i think it will allow you to create reservations in this excluded zone

[Edu-IT]

Great stuff, thanks!