The Structure Of An IPv4 Address (Free Preview)

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In the earlier lesson we learned that TCP/IP hosts see the IPv4 address as a stream of 32 bits. On the other hand, we humans use the dotted decimal notation to express an IPv4 address. However, the way we choose to represent this IPv4 address it has two components.

  1. Network ID (network address)
  2. Host ID (host address)


Figure IPv4 Address /24

Figure Binary representation of IPv4 Address /24




Network ID: All hosts in the same network share the same network ID. A network boundary is defined by a router.

Host ID: Identifies an end device such as a server, workstation, tablet, router, switch within a network. The host ID must be unique within a network. This is similar to the street address. For example, in Pennsylvania Avenue there can only be one property with a street address of 1600. That is the White House.

Note: The “/24” in the IPv4 address “ /24” represents the subnet mask. The same subnet mask can be written as The subnet mask helps us identify what is the network ID from a given IPv4 address. We will look at the subnet mask in greater detail once we have mastered the binary and decimal conversions.


In order to understand IP addressing further we need to thoroughly understand how to convert between binary to decimal and decimal to binary. In the next few lessons let’s look at how to do this.

Lesson tags: CCNA, CCNP, Cisco, IPv4, IPv6, TCP/IP
Back to: CCNA Routing and Switching 200-125 > IPv4 Addressing