Can I add multiple IPs to a server in this manner?

Question

Sorry the question is a little vague, I just don't know the terminology (and that is what has made my google searching difficult). I'm a web developer and maintain a network as a hobby.

I have several servers, two of which are IIS/MSSQL servers. They are virtual machines. I am using VMWare Server 2.0 now, but am in the process of moving over to Hyper-V. Hopefully this is not relevant.

Anyway, my network is 192.168.0.x. My router (ISA Server) is 192.168.0.1. Then my servers and workstations are in the range 192.168.0.2 - 192.168.0.99. They either have static IPs, or DHCP reservations. For example, the computer I am on right now is 192.168.0.26 (apparently it's also fe80::5d39:150f:5d24:a2eb%11 but I know even LESS about IPv6).

For the longest time, this has been adequate. But now, I am running many, many SSL enabled sites on my internal web servers. I am using SSL to SSL bridging with my ISA server, so I am having to assign several IPs to each of my web/sql servers, so that they can each support multiple SSL sites on the default port. Each has a range of 10 or so IPs now and they are needing more as time goes on, and pretty soon I am going to "run out". I would like a little more breathing room.

Is there any problem with taking my web/sql servers out of 192.168.0.x?

I would like to change the IP of my first web/sql server to 192.168.1.1. Then I can add a whole 'nother 200some IPs if I really need to, right?

I can make my second web/sql server 192.168.2.1, and do the same thing there. Then they could each run very many SSL sites. Or maybe I could leave their default IPs 192.168.0.30 and 192.168.0.50 respectively, as they are now, but just add IPs in this 192.168.1.x and 192.168.2.x section?

Does this make sense? Will there be any trouble with the fact that all my computers will no longer be 192.168.0.x? Is there an advantage to keeping them all 192.168.0.x when possible?

Could you please help me out with the terminology as well? 192.168.0.x is one _____ while 192.168.1.x is another _____, but they are still in the same ______ because they are both 192.168.x.x. What is the "/24" people talk about with IPs?

I apologize if this is a super common question. I just don't know the terms so it's hard for me to search. Thank you for your patience. I have learned a lot as I have hacked together this network so I really hope to be able to contribute back somehow.

Answer 1

You might want to read up on subnetting IP, if you're really curious how this works. It's fairly straightforward to follow. (Somebody wrote a fairly nice post, I think, about it here on Server Fault...)

The easiest thing to do is to change the subnet mask on all your server computer's internal network interfaces to something with more bits of host ID. Right now, they're all probably set to "255.255.255.0". You could back that off to "255.255.254.0", retain the current IP addresses in use, but also be immediately able to use the addresses 192.168.1.1 - 192.168.1.254 (and, technically, 192.168.0.255 and 192.168.1.0, too).

You should change the ISA Server machine first, then your DHCP server and DHCP scope (if you want to hand out addresses in the 192.168.1.0/24 range with DHCP), and then finally all your other server computers (which don't have to be changed immediately but won't be able to communicate with machines in the 192.168.1.0/24 range until you do).

(BTW: If you want to use all 192.168.X.X addresses, change the subnet masks to "255.255.0.0", and then any "192.168.X.X" address will be on your LAN.)