Upon completion of this chapter, you will be able to answer the following questions:
• What is the purpose of an IPv4 address?
• How are IPv4 addresses and subnets are used together?
Kishori is learning a lot from Rina! She understands that when she sends or receives a package in the mail, there is a unique address involved. A postal code is critical in the address to route the package to the correct post office. She asks Rina if computers use something like a zip code to route the message to the correct place. Rina goes into more detail about the process and explains that much like Kishori’s home address identifies where she lives, an IPv4 address identifies a host on the network. A host needs an IPv4 address to participate on the internet and almost all LANs today. Every packet sent across the internet has a source and destination IPv4 address. This information is required by networking devices to ensure the information gets to the destination and any replies are returned to the source.
My friend Kishori never thought she would be so interested in all of this tech information, but she really wants to learn more! Do you? Take this module to learn about the Internet Protocol and the structure of IPv4 addresses!
Purpose of an IPv4 Address (8.1)
Devices on the same network or different networks use IPv4 addresses to communicate. Messages are sent from the IPv4 address of the source to the IPv4 address of the destination.
A host needs an IPv4 address to participate on the internet and almost all LANs today. The IPv4 address is a logical network address that identifies a particular host. It must be properly configured and unique within the LAN, for local communication. It must also be properly configured and unique in the world, for remote communication. This is how a host is able to communicate with other devices on the internet.
An IPv4 address is assigned to the network interface connection for a host. This connection is usually a network interface card (NIC) installed in the device. Examples of end-user devices with network interfaces include workstations, servers, network printers, and IP phones. Some servers can have more than one NIC and each of these has its own IPv4 address. Router interfaces that provide connections to an IP network will also have an IPv4 address.
Every packet sent across the internet has a source and destination IPv4 address. This information is required by networking devices to ensure the information gets to the destination and any replies are returned to the source.
Octets and Dotted-Decimal Notation (8.1.2)
IPv4 addresses are 32 bits in length. Here is an IPv4 address in binary:
11010001101001011100100000000001
Notice how difficult this address is to read. Imagine having to configure devices with a series of 32 bits! For this reason, the 32 bits are grouped into four 8-bit bytes called octets like this:
11010001.10100101.11001000.00000001
That’s better, but still difficult to read. That’s why we convert each octet into its decimal value, separated by a decimal point or period. The above binary IPv4 becomes this dotted-decimal representation:
209.165.200.1
Note
For now, you do not need to know how to convert between binary and decimal number systems.
In this activity, you will observe how packets are sent across the internet using IP addresses.
Refer to the online course to complete this activity.