Networking Module 4: IPv4 Configuration on a Host

For a device to join an IPv4 network, its IP settings must be correct. If any of these values are wrong the host may only talk to some devices or may not have any network connectivity at all.

In this module you will look at the core IPv4 settings that a host needs, how the subnet mask defines the network portion and host portion, and how network, host and broadcast addresses are used.

🔎 What you will learn

• The three core IPv4 settings every host needs
• How the subnet mask separates network and host bits
• The difference between network, host and broadcast addresses
• How IPv4 address classes group ranges of addresses

🧠 Core IPv4 settings on a host

A typical IPv4 host needs three key settings:

• Unique IPv4 address identifies the device on the network.
• Subnet mask tells the host which part of the address is the network portion and which part is the host portion.
• Default gateway is the IPv4 address of the local router interface that forwards traffic to other networks.

📡 Network, host and broadcast addresses

In a network such as 192.168.10.0/24 there are special addresses that cannot be assigned to hosts.

• Network address: all host bits are 0, for example 192.168.10.0.
• First host: the first usable address, for example 192.168.10.1.
• Last host: the last usable address before the broadcast, for example 192.168.10.254.
• Broadcast address: all host bits are 1, for example 192.168.10.255.

🏷️ IPv4 address classes

Historically the IPv4 address space was divided into classes. You will still sometimes see these used in documentation and exams.

• Class A: very large networks, up to about 16 million hosts.
• Class B: medium sized networks, up to about 65 thousand hosts.
• Class C: smaller networks, up to 254 hosts.
• Class D: multicast traffic.
• Class E: experimental and reserved.