What Is an IP Address?

An Internet Protocol (IP) address is the unique identifying number assigned to every device connected to the internet. An IP address definition is a numeric label assigned to devices that use the internet to communicate. Computers that communicate over the internet or via local networks share information to a specific location using IP addresses.

IP addresses have two distinct versions or standards. The Internet Protocol version 4 (IPv4) address is the older of the two, which has space for up to 4 billion IP addresses and is assigned to all computers. The more recent Internet Protocol version 6 (IPv6) has space for trillions of IP addresses, which accounts for the new breed of devices in addition to computers. There are also several types of IP addresses, including public, private, static, and dynamic IP addresses.

 

Public IP Address

A public IP address, or external-facing IP address, applies to the main device people use to connect their business or home internet network to their internet service provider (ISP). In most cases, this will be the router. All devices that connect to a router communicate with other IP addresses using the router’s IP address.

Knowing an external-facing IP address is crucial for people to open ports used for online gaming, email and web servers, media streaming, and creating remote connections.

 

Private IP Address

A public IP address, or external-facing IP address, applies to the main device people use to connect their business or home internet network to their internet service provider (ISP). In most cases, this will be the router. All devices that connect to a router communicate with other IP addresses using the router’s IP address.

Knowing an external-facing IP address is crucial for people to open ports used for online gaming, email and web servers, media streaming, and creating remote connections.

 

Static IP Address

All public and private addresses are defined as static or dynamic. An IP address that a person manually configures and fixes to their device’s network is referred to as a static IP address. A static IP address cannot be changed automatically.

 

Dynamic IP Address

A dynamic IP address is automatically assigned to a network when a router is set up. The Dynamic Host Configuration Protocol (DHCP) assigns the distribution of this dynamic set of IP addresses. The DHCP can be the router that provides IP addresses to networks across a home or an organization.

What Is IPv4?

IPv4 is the fourth version of the IP. It is one of the core protocols of the standards-based methods used to interconnect the internet and other networks. The protocol was first deployed on the Atlantic Packet Satellite Network (SATNET), which was a satellite network that formed a segment of the initial stages of the internet, in 1982. It is still used to route most internet traffic despite the existence of IPv6.

IPv4 is currently assigned to all computers. An IPv4 address uses 32-bit binary numbers to form a unique IP address. It takes the format of four sets of numbers, each of which ranges from 0 to 255 and represents an eight-digit binary number, separated by a period point. 

IP Address Classes

Some IP addresses are reserved by the Internet Assigned Numbers Authority (IANA). These are typically reserved for networks that carry a specific purpose on the Transmission Control Protocol/Internet Protocol (TCP/IP), which is used to interconnect devices. Four of these IP address classes include:

  1. 0.0.0.0: This IP address in IPv4 is also known as the default network. It is the non-routable meta address that designates an invalid, non-applicable, or unknown network target.
  2. 127.0.0.1: This IP address is known as the loopback address, which a computer uses to identify itself regardless of whether it has been assigned an IP address.
  3. 169.254.0.1 to 169.254.254.254: A range of addresses that are automatically assigned if a computer is unsuccessful in an attempt to receive an address from the DHCP.
  4. 255.255.255.255: An address dedicated to messages that need to be sent to every computer on a network or broadcasted across a network.

Further reserved IP addresses are for what is known as subnet classes. Subnetworks are small computer networks that connect to a bigger network via a router. The subnet can be assigned its own IP address system, so that all devices connecting to it can communicate with each other without having to send data via the wider network. 

The router on a TCP/IP network can be configured to ensure it recognizes subnets, then route the traffic onto the appropriate network. IP addresses are reserved for the following subnets:

  1. Class A: IP addresses between 10.0.0.0 and 10.255.255.255
  2. Class B: IP addresses between 172.16.0.0 and 172.31.255.255
  3. Class C: IP addresses between 192.186.0.0 and 192.168.255.255
  4. Class D or multicast: IP addresses between 224.0.0.0 and 239.255.255.255
  5. Class E, which are reserved for experimental usage: IP addresses between 240.0.0.0 and 254.255.255.254

IP addresses listed under Class A, Class B, and Class C are most commonly used in the creation of subnets. Addresses within the multicast or Class D have specific usage rules outlined in the Internet Engineering Task Force (IETF) guidelines, while the release of Class E addresses for public use was the cause of plenty of debate before the IPv6 standard was introduced.

Internet Addresses and Subnets

The IANA reserves specific IP address blocks for commercial organizations, government departments, and ISPs. When a user connects to the internet, their ISP assigns them an address from within one of the blocks assigned to it. If they only go online from one computer, then they can use the address assigned to it by their ISP. 

However, most homes now use routers that share a network connection with multiple devices. So if a router is used to share the connection, then the ISP assigns the IP address to the router, and then a subnet is created for all computers that connect to it. 

IP addresses that fall within a subnet have a network and a node. The subnet is identified by the network. The node, also known as the host, connects to the network and needs its own address. Computers separate the network and node via a subnet mask, which filters the appropriate IP address designation. When a large network is set up, the subnet mask that best fits the number of nodes or subnets required is determined. 

When it comes to IP addresses within a subnet, the first address is reserved for the subnet, and the final one indicates the broadcast address for the subnet’s systems.

IPv4 vs. IPv6

IPv4 has not been able to cope with the massive explosion in the quantity and range of devices beyond simply mobile phones, desktop computers, and laptops. The original IP address format was not able to handle the number of IP addresses being created.

To address this problem, IPv6 was introduced. This new standard operates a hexadecimal format that means billions of unique IP addresses can now be created. As a result, the IPv4 system that could support up to around 4.3 billion unique numbers has been replaced by an alternative that, theoretically, offers unlimited IP addresses.

That is because an IPv6 IP address consists of eight groups that contain four hexadecimal digits, which use 16 distinct symbols of 0 to 9 followed by A to F to represent values of 10 to 15.

How Do I Locate My IP Address?

Windows computer users can look up their IP address by typing "cmd" into the search tab and hitting Enter, then typing "ipconfig" into the pop-up box. Mac computer users can find their IP address by heading into System Preferences and selecting Network. 

To look up an IP address on a mobile phone, users need to head into Settings, then open the Wi-Fi menu and their network menu. The IP address should be listed under the Advanced section, depending on the phone they use.

How Fortinet Can Help

Fortinet helps to keep business devices and end-users secure from external and internal threats. The Fortinet next-generation firewall (NGFW) provides deeper insight and visibility into what is happening on businesses' networks, enabling them to identify potential attacks and the presence of malware or other risks more quickly.

Key Takeaways

Every device that connects people to the internet has a unique identifying number known as an IP address. This numeric label is used by computers to communicate with each other and share information over the internet or on local networks.

Computers are commonly assigned an IPv4 IP address, which is the original standard for identifying internet-connected devices. However, due to the huge growth in the number of and types of devices, the new standard IPv6 is increasingly being used.

FAQs

What is the use of an IP address?

An IP address identifies every device connected to the internet. This enables computers and other internet-connected devices, such as mobile phones and Internet-of-Things (IoT) devices, to communicate over the internet and on local-area networks (LANs). 

What happens if someone has your IP address?

The chances of being hacked through someone having your IP address is quite low. With an IP address, a user's location can be narrowed down to a specific area. A skilled cyber criminal could potentially work out who their ISP is and then use phishing attacks to find their personal details. A bigger concern might be IP addresses being sold on the dark web alongside other personal information. 

An IP address is more likely to be used by content providers to target the user with content restrictions based on their geographical region. For example, services like Hulu and Netflix read IP addresses to prevent their U.S. content from being accessed by people outside the country. 

What are the two types of IP addresses?

The two types of IP addresses are public IP addresses and private IP addresses. A public IP address is the main device people use to connect to the internet, which is typically their router. Private IP addresses are assigned to the devices that connect to the public IP address, such as desktop computers, mobile devices, laptops, printers, smart TVs, and tablets.

What is the 192.168 IP address?

The 192.168 IP address is where the private IP address range begins. This goes all the way through to 192.168.255.255. This IP address is not usually used on a network, and devices like computers and mobile phones will not be assigned it.

What is a loopback IP address?

The loopback IP address is 127.0.0.1. The loopback IP address is used by a computer to identify itself, regardless of whether or not it has been assigned an IP address.