IP addresses and local networks
Read an interface address and prefix, then decide which destinations belong to the local network.
- Read an IPv4 interface address with a prefix length.
- Explain why the prefix is needed to decide whether a destination is local.
- Network foundations
- Network interface
- Packet
On this page
Address plus context
An IPv4 address identifies an interface in an IP network context. The prefix length tells the host how many leading bits describe the local network.
Our simulator uses:
Interface: lab0
IPv4: 192.0.2.10/24192.0.2.10 is the interface address. /24 is the prefix length. Together they tell the host that destinations in 192.0.2.0/24 are local to this exercise.
What the prefix changes
An address alone is not enough to decide whether another address is local. The prefix supplies that boundary. If a destination is local, the host can try to reach it on the local network. If it is not local, the host needs a route—usually through a default gateway.
Try it
Common mistakes
/24is not part of the device name; it describes a network prefix length.- An IP address identifies an interface in context, not automatically a person or an entire physical machine.
- Receiving a ping reply does not prove that every application or port works.
Quick check
In the fixture, identify the host address, prefix and gateway. Which one is the local computer's interface address?
Next stepGateway and routerFollow a packet from the host to another network.