Convert your DHCP based network to a STATIC IP based LAN

DHCP Servers automate the process of setting up the 'IP Schema' of your home network. When your computer is turned on, it seeks a DHCP server on the network and gets a 'dynamic' IP address. Each time the computer is turned on, it could get a different IP address depending on a bunch of other factors. Usually your Internet connection sharing solution is responsible for having a DHCP server built in. All broadband routers come with DHCP Servers and almost every software solution like Microsoft Internet Connection Sharing (ICS) does too.

To see your current IP address, go to a command prompt and type IPCONFIG

DHCP Servers and Advanced Applications

The primary reason for switching from a DYNAMIC (DHCP) addressing schema to a static one is the ability to run servers and other advanced applications behind a NAT firewall. When you run any kind of server, a hole must be punched in your firewall and pointed at the computer with the server running - this is called port forwarding. If the IP address of the server changes, the hole will be pointing to the wrong place!

Static IP address' require a small amount of configuration and management up front for a small network but allow the reliable configuration of game and application servers.

Side Note: an IP address is composed of 4 octets, each ranging between 0 and 255. A zero is never used in the first or last octet.

IP Ranges

There are three 'ranges' that are deemed private and are usable for home networks. They are as follows.

192.168.x.x

172.16.x.x

10.x.x.x

The most popular IP address schema set as the default schema is 192.168.x.x, often 192.168.10.x or often 192.168.1.x. Routers and other internet sharing solutions are usually positioned as the first IP address in the schema - in our example it will be 192.168.10.1.

First go to your router's administration page and configure the built in DHCP server. Each router will be a little different and hay have different capabilities. You should leave the DHCP server enabled, but limit the number of IP address it can distribute.

If we allow our DHCP server to start numbering computers at 192.168.10.2 and allow 50 IP address, the last DHCP reserved address will be 192.168.10.52. Sometimes this is done as a 'range' instead of a 'number of computers' setting. To make it easy on ourselves, we might want to start numbering static addressed computers at 192.168.10.100 - well out of the DHCP Range

Our IP schema looks like this

192.168.10.0 subnet 255.255.255.0 is our 'network'.

192.168.10.1 is our router

192.168.10.2 to .52 are DHCP reserved address

192.168.10.100 to .255 are the STATIC address

Setting up a computer:

When we change a computer from DHCP to Static IP, we must type in FOUR pieces of information. IP address, Subnet, Default Gateway, and DNS Server. The IP address will be one from our static IP range, the subnet will be 255.255.255.0 and the Gateway and DNS will be the address of our router - 192.168.10.1

Get the TCP/IP properties of your computer and set them up with the four required pieces of information.

Computer 1

IP: 192.168.10.100

Subnet: 255.255.255.0

Gateway: 192.168.10.1

DNS: 192.168.10.1

Computer 2

IP: 192.168.10.101

Subnet: 255.255.255.0

Gateway: 192.168.10.1

DNS: 192.168.10.1

 

Etc.

THAT’S ALL FOLKS!

Sometimes is necessary or even just beneficial to move your IP schema away from the default that your router comes with. For instance, instead of running the default 192.168.1.0 subnet, you might want to change the third octet to something else. I do this with ALL the networks I set up for both security and routing purposes.

First, pick an third octet - choose something between 11 and 255, anything below 11 is fairly common.

Next, set the internal LAN IP ADDRESS of your ROUTER using the router's administration pages. Next, set your computer up with a STATIC address in that same range and reboot both machines (not necessary to reboot Win2k or WinXP). Lastly, ensure that the DHCP range in your router is set up correctly. Remember, the administration screens are at the NEW router address, not the old one.

 

Convert your DHCP based network to a STATIC IP based LAN