Re: 255.255.254.0 subnet mask vs 255.255.255.0 subnet mask

[Clay Carley <cbc@xxxxxxxxx>]

The difference is really just the number of hosts you can have on the 
subnet.
255.255.255.0 can have 254 hosts (i.e., 192.168.0.1 - 192.168.0.254)
255.255.254.0 can have 510 hosts (i.e., 192.168.0.1 - 192.168.1.254)

As long as all of your hosts on the DMZ have the same first 3 octets of 
their IP address, you should be fine.  If any do have a different 3rd 
octet, they will be broken after the mask change.

Does that help?

Clay Carley

On 2019-01-03 11:37, Rob Berendt wrote:

> Network guy had me set up our DMZ based LPARs with a 255.255.254.0 
> mask.
> Now he wants me to change it to a 255.255.255.0 subnet mask.
> I told him that it would have to wait until our next scheduled 
> downtime.
> Which is in March.
>
> I am trying to figure out why.  I can't get an explanation from him 
> that I
> can understand.  Knowing why might help me to determine what I should 
> test
> to see what it broke.  For example, since he discovered this by 
> analyzing
> traffic I am assuming that something is using this.
>
> Rob Berendt
> --
> IBM Certified System Administrator - IBM i 6.1
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