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IP addresses are like opinions…everyone has one. But not all IP addresses are equal. Some IP addresses are dynamic, meaning they change automatically based on router settings.
Also: Static vs Dynamic IP Addresses: Why You Need to Know the Difference
Sometimes dynamic addresses are a problem. What if you have a computer on your network with a directory (or directories) shared with other machines? Or maybe you have a printer connected to a computer that you always need access to? Suppose the network share or printer is associated with a computer that is assigned a dynamic IP address. In this case, you might find yourself in a situation where you have to reconnect with the new assigned IP address.
This is where static IP addresses come into play. You set them manually so they never change. But we need to consider some nuances and caveats when it comes to static IP addresses.
IP address conflicts
Let's say you have a 192.168.1.1 IP address scheme dynamically assigned by your router. You may want to assign a computer with an associated share the address 192.168.1.101. But what happens if this address is already taken? Or what happens if your router assigns the same address to another machine after configuring it manually? When this happens, you get IP address conflicts.
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To work around this problem, you must know how to configure your router so that it is limited to, for example, 192.168.1.1 to 192.168.1.100 for dynamic address assignments. You can then assign any IP address greater than 0.100 to any machine on your network, without worrying about conflicts.
Every operating system is different
The second problem is that setting up a static IP address is different for each operating system on your network. Most of the configuration is the same:
- Open settings
- Locate the network
- Find network settings
- Access IPv4
- Select Manual (or Static, depending on your operating system)
- Enter the necessary details
- Save the configuration
Some operating systems may also require you to stop and restart networking before changes begin.
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Here is the information you need to configure a static IP address:
- IP adress – This is the IP address that you will assign to the machine, in the form XXX.XXX.XX.X.
- Default Gateway – Usually the IP address of your modem or router.
- Network Mask – A 32-bit number that divides an IP address into subnets (smaller private networks) and specifies the hosts available on a network. Typically, a netmask has the form 255.255.255.0.
- DNS – This is the server address used for DNS (Domain Name System) which translates google.com into 64.233.185.101. Without DNS, the Internet would not be able to find google.com.
Internal vs. external
Another nuance is important to understand. Some IP addresses are accessible to the outside world, while others are only accessible to the inside world. Remember the DNS translated address for google.com, 64.233.185.101? This is an external IP address. The address 192.168.1.101? It's internal.
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A router (or modem) generally has two network interfaces: one for external and one for internal. The external interface is assigned an external (i.e. public) address, which is discoverable to the outside world. The internal (aka private) interface is what your machines connect to. These internal machines send data to the internal interface, which is then routed through the external interface, where they can find websites, servers, and services.
RFC1918 allows the following private address ranges (which can be static or dynamic):
- 10.0.0.0/8 (like 10.1.1.10)
- 172.16.0.0/12 (like 172.16.0.10 but never 172.0.0.0 because these addresses are reserved for what we call looping)
- 192.168.0.0/16 (such as 192.168.1.101)
All public IP addresses (all of which are static) fall into one of the following ranges:
- 1.0.0.0 to 9.255.255.255
- 11.0.0.0 to 100.63.255.255
- 100.128.0.0 to 126.255.255.255
- 128.0.0.0 to 169.253.255.255
- 169.255.0.0 to 172.15.255.255
- 172.32.0.0 to 191.255.255.255
- 192.0.1.0/24
- 192.0.3.0 to 192.88.98.255
- 192.88.100.0 to 192.167.255.255
- 192.169.0.0 to 198.17.255.255
- 198.20.0.0 to 198.51.99.255
- 198.51.101.0 to 203.0.112.255
- 203.0.114.0 to 223.255.255.255
Our example of google.com (64.233.185.101) is between 11.0.0.0 and 100.63.255.255. You can find the public IP address of many domains by issuing a command like:
ping google.com
A neat trick for locating your network's public IP address is to open your web browser and navigate to addressip.comwhere you will see your public IP address displayed along with your location and Internet Service Provider.
Switch to a static IP address
As mentioned earlier, you should consider the caveats before changing a static address. But if you have taken care of these things and are ready to change, you can follow the instructions I described in my article: “How to change your IP address, why you would want to do it – and when you shouldn't do it'. You will find instructions for most operating systems in this article.
Remember to keep IP address conflicts in mind before changing this IP address from manual to static, otherwise problems may arise.
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And that's the gist of static IP addresses. Unless you have a computer or device on your network that must always have the same IP address (so it's easy to find), you shouldn't worry about static IP addresses. But if you need to assign an address to a computer, you will now have a good idea of what it is and how it works.