IP Explained: How It Works and What to Look For
Internet Protocol moves packets between hosts across interconnected networks.
Published by Protocol Explorer · Reviewed
How IP works
An IPv4 sender supplies source and destination addresses; routers forward each packet toward its destination. IPv4 does not itself guarantee delivery or ordering.
What to look for in an exchange
Read the version, total length, source and destination addresses and TTL. Routers decrement TTL, limiting how long a packet can circulate.
Follow an example step by step
- Read the IP version and destination address to determine which host the sender is trying to reach.
- Inspect TTL, protocol and total length before following the encapsulated transport.
- Compare the addresses and TTL at different capture points to understand forwarding across routers.
Common interpretation mistake
IP delivery is best effort: a sender cannot infer application success solely from sending an IP packet.
Key point to remember
IPv4 fragmentation and reassembly have specific rules; avoid treating every captured fragment as a complete transport message.
Explore the protocol
The IP overview is free without an account. Its full interactive lesson is included in Protocol Explorer Pro, a one-time $4.99 purchase; an account is required to buy Pro and restore the licence across devices.
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Specification
Read the primary specification for IP for the authoritative protocol details. The interactive scenario is a simplified teaching model, not a capture of your network.
Continue learning
How to read a packet · TCP · UDP · HTTPS