Working with Static Internet Protocol (IP) Addresses

A static IP address (sometimes also called a fixed IP address) is an Internet Protocol (IP) address number assigned to a network device by an administrator. Static IP is an alternative to dynamic IP assignment on Internet Protocol networks.

Static vs. DHCP Addressing

Most IP networks use dynamic addressing via DHCP rather than static IP assignment. Dynamic addressing is convenient as it's easy for administrators to set up.

 DHCP works automatically with minimal intervention needed, allowing mobile devices to more easily move between different networks.

However, static IP addressing offers some advantages, too:

• A static IP address best supports name resolution across wide area networks (WANs), enabling devices to be reliably reached by their assigned host names. Web and FTP servers often use fixed addressing for this reason.
• Using static IP addresses on home networks slightly better protection against network security problems than does DHCP address assignment.
• Some network devices do not support DHCP. Using static IP assignment for all devices on the home network avoids potential IP address conflicts where DHCP might supply an address already assigned statically elsewhere.

Using Static IP Address Assignment on Home Networks

When making static IP assignments for local devices on home and other private networks, the address numbers should be chosen from within the private IP address ranges defined by the Internet Protocol standard:

• 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 number within them can be chosen and that 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. 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 local network. For example, to support all addresses in the 10.x.x.x private range, the subnet mask on all devices must be set to 255.0.0.0, otherwise some static IP addresses in this range will not work.

Static IP Addresses on the Internet

Internet providers traditionally assign all of their IP address to customers dynamically. This is due to historical shortages of available IP numbers. Having a static IP based Internet service is most useful for remote access such as monitoring a household's IP cameras.

Customers can sometimes obtain a static IP by subscribing to a special service plan and paying extra fees - check with the provider for details.