Classful Addressing

What this foundational networking question tests

This is an easy question about the structure of IPv4 unicast addresses. It probes whether you understand the fundamental anatomy of IP addresses and how they encode routing information. Questions in this area are common in networking interviews, especially at firms building trading infrastructure or working on low-latency systems where network understanding matters.

To answer it, you need to recognize that every unicast IP address serves two distinct logical purposes in the network. One part identifies the network itself; the other identifies a specific host on that network. Understanding this split is foundational for grasping how routers make forwarding decisions and how subnetting works.

• Classful vs. classless addressing schemes
• Network masks and prefix length
• How routers use address structure to determine reachability