You're too big!

What this IP fragmentation interview question tests

This is a hard networking question that probes your understanding of how the Internet Protocol handles packets that exceed the maximum transmission unit (MTU) of a link. It's the kind of question that surfaces in infrastructure and systems interviews where candidates need to reason about real-world packet behaviour rather than abstract protocols.

The question rewards clarity on the mechanisms the IP layer uses to deal with size mismatches, the trade-offs involved, and how modern networks try to avoid the problem altogether. You should be able to explain both the mechanics and the practical implications—what happens at each layer, what fields matter, and why this became a critical consideration in protocol design.

• MTU discovery and path MTU
• Packet headers and size constraints
• Fragmentation flags and offset fields
• Reassembly at the destination