A fixed IP address or the static IP address is an Internet Protocol address which is assigned to any network device and can not change. It is called fixed because it is “fixed” and does not change. This is in contrast to having a dynamic IP address where the IP address can change every time a device connects and reconnects to the network.
Any device which can use an IP address can be configured to have a fixed IP address.
Despite it being expensive and insecure, there are situations when using a static IP address is beneficial. For example
- Email/chat servers, game servers, etc.
- Provisioning dedicated services like FTP or web servers etc
- Geolocation services as it makes it easier to assess your position accurately
- Finding DNS hosts that will translate domain names to IP addresses
Before knowing how to obtain a fixed IP address, let us discuss further on fixed IP address first.
What is a Fixed IP address?
As the name itself suggests, IP address assigned to the device is permanent and does not change. The device with a fixed IP address always connects to the internet with the same IP address.
No one had ever imagined how many IP addresses would be needed in future and so when Ipv4 came into the picture, it sounded containing an inexhaustible number of ip addresses. It is to be noted that Internet Protocol version 4 (IPv4), based on 32-bit addressing allows for 4.2 billion unique IP addresses.
Even though this number sounds huge, ISP still adopts a conservative approach in allocation static IP address.
As the total number of IP addresses offered by IPv4 is fixed, it could have exhausted has there been the only provision of providing fixed IP addresses.
DHCP keep allocating and deallocating IP addresses as and when different network devices join and leave the network and that way DHCP can serve more devices.
And that’s how IP address is reused again and again floating between different devices.
With the recent expansion of devices capable of connecting to the network, limitation of Ipv4 was clearly visible. That led to the development of a new protocol called Ipv6 which is based on 128 bit of addressing and so expanding the IP address limit to virtually unlimited.
We hope that the allocation of static IP address will be easier and readily available in Ipv6.
Fixed IP address is expensive, and at the same time, it has high-security risks. It is because the address never changes and can be prone to hacking.
Fixed IP address & the home network
How long can your computer retain the same IP address?
The network router at home is capable of keeping track of how long an IP address is assigned to a particular device. DHCP is in charge of monitoring that the network does not run out of IP addresses.
For this, DHCP sets a “lease” (a time limit) to determine the time a computer can retain the same address. After the lease exceeds, the address is re-assigned to another device seeking for it.
Routers usually set short lease like 24-hours. They also permit administrators to change the default value. But this method is helpful for an extensive network where several devices are connecting to and disconnecting from it. It may not be needed for the home network.
By changing the DHCP lease value to a longer time, the ambit of each computer to retain its same address extends more, maybe indefinitely.
Static IP address as an alternative for DHCP
One can opt for static IP for a home network instead of DHCP. Having static IP will guarantee a fixed address. It will not change even if the device gets disconnected sometimes.
Allocating static IP address for all devices on the home network will reduce the occurrence of IP address conflicts. It occurs when DHCP issues an address, which is already assigned statically elsewhere.
To change DHCP lease time or network to static addressing, log in to the home router as administrator. Then, update to the required settings. You should read your respective router manual to do the same.
Your router should ask for an IP address along with MAC address of your device to assign a static IP address to it.
Fixed IP address & public networks
Public IP addresses are needed for any publicly accessible network hardware. It may be the home router or servers hosting website. They are assigned by the ISP and are prone to change.
One needs a special service plan and extra fees to get a static IP from ISP.
It is also not possible for devices to have the same public IP address while roaming between different public networks.
Mobile devices that connect to the public Wi-fi hotspots will have their IP addresses changed as soon as they are switching networks.
Rules for fixed IP address allocation for home network
Ranges of IP addresses
The address numbers must be selected from the ranges of private IP addresses defined by the Internet Protocol standard during static IP address assignment.
The ranges are:
- 0.0.0 to 10.255.255.255
- 16.0.0 to 172.31.255.255
- 168.0.0 to 192.168.255.255
These ranges are an abundant supply of different IP addresses. People may think that any one of them can be chosen randomly. However, this is not true.
To choose and set a specific IP address for a particular network, some rules are to be followed.
Rules for choosing static IP address
- Avoid addresses ending with ‘.0′ or ‘.255′. These are usually reserved for use by network protocols.
- Do not select addresses at the beginning of a private range. Want to know why? Well, they are usually in use by network routers and other consumer devices.
These addresses, like 10.0.0.1 and 192.168.0.1, are highly susceptible to hacking when hackers attempt to break into a private network.
- Avoid choosing an address which is outside the range of your local network. To support all addresses in the range 10.x.x.x, subnet mask on all the devices should be set to 255.0.0.0. Otherwise, few static IP addresses may not function properly.
How to assign a static IP address to a Windows PC?
Finding router IP address
- Open the command prompt on the PC
- Click on Start → Type cmd
- The command prompt appears.
- Type ipconfig
- The required IP address is corresponding to the ‘default gateway’ field.
- Open a web browser
- Type the IP address in the address bar and press enter.
- The web interface for the wireless router is loaded.
- Enter router username and password to gain access.
Set the static IP address
- Search for the section showing current IP addresses allocated by DHCP server
Considering an AT&T router as an example,
- Go to Settings → LAN → IP Address allocation
- Find a fixed ip address from the list to be provided to a device.
- Click on Address Assignment drop-down. It is “private from pool: IP Range” by default.
- Select a fixed IP from the drop-down. Note that it is not the one which has been already allotted to another device in the network.
Fixed IP address & VPN
VPN (virtual private network) generally route all traffic through a defined IP address. It is beneficial for use cases where a source or destination IP address must be whitelisted. For example, let’s say you stay in the United States and want to watch a TV program which is restricted in the United States. A VPN can do the trick for you.
Similarly, some specific security products demand that a particular identified IP address or IP range can only access it. If ISP does not provide a fixed public IP address, using a VPN can aid in overcoming this obstruction.
Suggested reading: How does VPN benefit you?
Thus, in the above discussion, we get acquainted with the scenario of using fixed IP addresses on home networks as well as public networks. Also, you get to know that VPN can be used to route traffic through a specified IP address.
The fixed IP address is expensive and prone to security threats. So, you should be judicious in choosing one.
Moreover, limited available IP address in the IPv4 range also forced ISPs to assign a reusable dynamic IP address to the network devices. It uses DHCP in provisioning dynamic IP addresses.
Challenge yourself – Task for you
Visit your home router administrative console and find out how can you assign a fix IP address to one of your laptops. Reach out to us if you need any help