IP Addresses

The use of IP addresses is the primary means of enabling devices to locate one another and establish end-to-end communication on the Internet. Each end device on a network must be configured with an IP address. Examples of end devices are listed in Figure 1.
The structure of an IPv4 address is called dotted decimal notation and is represented by four decimal numbers between 0 and 255. IPv4 addresses are assigned to individual devices connected to a network.
Note: IP in this course refers to both the IPv4 and IPv6 protocols. IPv6 is the most recent version of IP and the replacement for the more common IPv4.
With the IPv4 address, a subnet mask is also necessary. An IPv4 subnet mask is a 32-bit value that separates the network portion of the address from the host portion. Coupled with the IPv4 address, the subnet mask determines which particular subnet the device is a member.
The example in Figure 2 displays the IPv4 address (192.168.1.10), subnet mask (255.255.255.0), and default gateway (192.168.1.1) assigned to a host. The default gateway address is the IP address of the router that the host will use to access remote networks, including the Internet.
IP addresses can be assigned to both physical ports and virtual interfaces on devices. A virtual interface means that there is no physical hardware on the device associated with it.

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