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TCP/IP subnet question

My network is growing.  I am using dhcp and I have almost used all the available host ip addresses.
Everyone has a wifi need on their cellphones and it is adding up quickly.
I need to be able to have dhcp add more than the 254 and still be on my network.
How do I set up the subnet to handle that?
I am currently using - .254 and the router is on 1.1
1 Solution
The simplest solution would be to expand your subnet mask by a single byte.

Use -
You subnet mask would become simply

This will give you (aprox) 256*256 total IP addresses you can assign.

You could alternatively expand by only a single bit, which would double your number of available addresses:
Use -

Once you make the subnet changes to all the statically-addressed computers, you'll change your DHCP scopes to match it.

Be careful though,  too many devices on the same subnet can hinder network performance.  If this starts happening, you may need to consider breaking your network into separate subnets (one for wifi devices, one for wired workstations and server, for example)
I am not sure that is right. My understanding is the Class C 192.168.x.x series of addresses have a maximum of 256 addresses in a subnet. For larger number of addresses, you are supposed to use the Class A or B addresses: -
or -

See:  http://en.wikipedia.org/wiki/Private_network


Fred MarshallPrincipalCommented:
I believe that "Class C", etc. is an anachronism.  Best not think that way.

The private range of addresses that you are using is within:

I wouldn't go to that extent however.
I would likely change the network address to or .
This will double the number of addresses while keeping the current addresses intact to a point - in that to are all viable addresses within

So, if you have a printer with then you could change that to (or on the printer but any computers pointing to that address would not need to be changed.  Well, except their own subnet mask would be changed of course to but not the printer setup.  Just an example.....

During the transition you may find that everything works pretty well anyway before all the subnet masks are changed.  That can ease transition and is better than a wholesale change of the address range.  The process should start with the DHCP server's own subnet mask and the DHCP lease subnet mask and go from there giving highest priority to the core devices.
Dave BaldwinFixer of ProblemsCommented:
That "Class C" information is the "old way" of doing it.  The remarks about changing the network mask and DHCP range are correct and would apply even to the other private IP ranges you mentioned.  While the term "Class C" is still used in many places, it is not a technical method.  Classless Inter-Domain Routing (CIDR) was introduced in 1993 to make better use of the IP address space.  This page http://en.wikipedia.org/wiki/Classless_Inter-Domain_Routing has a chart that shows how to do subnetting or "IPv4 CIDR blocks".
You can perfectly expand your existing DHCP range/scope with a change in the subnet.

Check these resources:


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