DHCP Exclusion / not in scope

[TornUp]

With the new domain plan taking shape I was asked by my manager today if i know what the difference between a 1-254 scope with everything over 100 EXCLUDED

 

Then To

 

Creating a scope from 1-100 and leaving the rest out of scope (and therefore static)

 

I put it down to it being documented (showing in DHCP) if it is excluded. And its just ..... "Unknown" if its not in the exclusion..

 

Can anyone tell me if they know any different to what is above. is there any advantage to excisions?

[srochford]

We have pairs of DHCP servers. Each issues the same range but with half excluded (a different half on each!). If we didn't exclude then there's a risk of issuing the same address from 2 different servers which is a "bad idea"

 

If you're only using 1 server then I'd guess the exclusion just serves as a reminder "don't use this block of addresses they're used for xxxxx" which is a "good idea" because it means you won't acccidentally double allocate.

[Geoff]

If you're only using 1 server then I'd guess the exclusion just serves as a reminder "don't use this block of addresses they're used for xxxxx" which is a "good idea" because it means you won't acccidentally double allocate.

 

Indeed, I use ISC DHCPd and thats encouraged as best practice. Basically you define all your subnets so it is aware of them, however you only offer leases on the ones you want. That way the server has a full view of your network.

[apeo]

With the new domain plan taking shape I was asked by my manager today if i know what the difference between a 1-254 scope with everything over 100 EXCLUDED

 

Then To

 

Creating a scope from 1-100 and leaving the rest out of scope (and therefore static)

 

I put it down to it being documented (showing in DHCP) if it is excluded. And its just ..... "Unknown" if its not in the exclusion..

 

Can anyone tell me if they know any different to what is above. is there any advantage to excisions?

 

Technically theres no dif, imo its your personal choice as really you should have documentation for you ip addressing scheme so it doesnt really matter if its in dhcp or not (imo as it doesnt say why its excluded).

[toasteroven]

I leave the upper 20-30 addresses static in my scopes for servers, managed network devices, printers, etc. I've always seen it as standard practice where I've worked.

 

+1 for documentation

[DSapseid]

My DHCP scope is 192.168.168.0 - 192.168.172.254. With 192.168.168.0 - 192.168.168.254 not in the scope for servers, printers, switches, waps etc.