Greetings fellow system managers:

We have this discussion about the use of Class "A" vs. Class "C"
of IP addresses.

We have been using unregistered  class A IP adresses for our internal networks
for about a decade now. About 3 years ago, we started using registered
Class "C" IP addresses from NIC.

Our HP3000/HP9000 servers, like some of our users, are using class A addresses.
Other PCs are using class C thru a proxy server, so they can get to the
HP servers.

Our class A addresses are in the "10.x.x.x" thru "10.100.x.x" ranges.
Some of our users are able to go out into the Internet using the 10.x.x.x.
address, when the subnet mask is 255.0.0.0.

Our firewalls are on the class C IP addresses.

So the question is: Are there any reasons for us to convert to class C?
I say that security is enhanced if we could remain in Class A, and convert
class C PCs to class A, and leave the Internet machines in class C.

There are about 600+ PC and printers that have a mixed class A and C addreses.

Does anyone have a better idea? Thanks.