Using Static IP Addresses on Private Networks

Static IP address assignment (sometimes also called fixed addressing) is an alternative to dynamic addressing (normally, DHCP) on Internet Protocol networks. Dynamic addressing is convenient. It also allows mobile computers to more easily move between different networks.

However, static IP addressing also offers some advantages:

• A static IP address best supports name resolution, so that a computer can be most reliably reached over the network by its host / domain name. Web and FTP servers in particular benefit from fixed addressing for this reason.
  
  
• Using static IP addresses on home networks gives somewhat better protection against network security problems than does DHCP address assignment.
  
  
• Some network devices do not support DHCP. Using static IP address assignment for all devices on the home network guarantees to avoid potential address conflicts where DHCP may supply an address already assigned statically elsewhere.

When using static IP addresses on home and other private networks, they should be chosen from within the standard private IP address ranges listed:

• 10.0.0.0 through 10.255.255.255
• 172.16.0.0 through 172.31.255.255
• 192.168.0.0 through 192.168.255.255

These ranges support many thousands of different IP addresses. It's common for people to assume that any address in these ranges can be chosen and the specific choice doesn't matter much. This is untrue. To choose and set specific static IP addresses suitable for your network, follow these guidelines.

1. Do not choose any addresses that end with ".0" or ".255" - these addresses are generally reserved for use by network protocols.
   
   
2. Do not choose the addresses at the beginning of a private range. IP addresses like 10.0.0.1 and 192.168.0.1 are very commonly used by network routers and other consumer devices. These are the first addresses someone will attack when trying to break into a private computer network.
   
   
3. Do not choose an address that falls outside the range of your network mask. For example, to support all addresses in the 10.x.x.x private range, the network mask on all devices must be set to 255.0.0.0, otherwise some static IP addresses in this range will not work.