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DHCP Exclusion

munawar.zeeshan
Level 1
Level 1

I want to exclude some IPs from DHC on a switch 3750.

will this command work

ip dhcp excluded-address 172.28.140.0 172.28.140.9

or shuld i write like this

ip dhcp excluded-address 172.28.140.1 172.28.140.9

can anyone explain the difference ?

3 Replies 3

sgvoip001
Level 1
Level 1

Hi,

if the netmask is /24 (255.255.255.0) you can write the second one because 172.28.140.0 is the network address and won't assigned to a client by the DHCP algorithm.

The excluded command has following parameters

ip dhcp excluded-address

The first command would exclude the IP Adress x.x.x.0 until (inclusive) x.x.x.9 and the second one would exclude x.x.x.1 until (inclusive) x.x.x.9.

Olli

Ok. means the first way is the wrong method and it will not work ?

and it will exclude also the whole network , because of .0

Hi,

its not the wrong method and it will work but it isn't neccessary. You exclude only the IP itself and not the whole network. But the DHCP algorithm wouldn't assign this IP to a client and therefore it isn't neccessary.

Olli

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