The Internet: Packets, Protocols & DNS

The Internet is a network of networks. AP CSP's "Internet" big idea is about how data travels reliably across it — not about wiring details.

Packets

Data is broken into small packets. Each packet carries part of the message plus metadata (source, destination, ordering). Packets may travel different routes and arrive out of order; the receiver reassembles them.

Protocols

Protocols are agreed rules that let different devices communicate:

• IP (Internet Protocol): addresses and routes packets.
• TCP: ensures reliable, in-order delivery (re-sends lost packets).
• HTTP/HTTPS: rules for web pages (HTTPS is encrypted).

IP addresses & DNS

Every device has an IP address. DNS (Domain Name System) translates a human name like itmagic.com.tr into its IP address — like a phone book for the Internet.

Fault tolerance

The Internet is fault tolerant because of redundancy: multiple paths between points. If one path fails, packets route around it. This is why the Internet is hard to break by removing a single connection.

Exam tip

Know the vocabulary precisely: packet, protocol, IP, DNS, bandwidth, redundancy, fault tolerance, scalability. Understand that open protocols let the Internet scale, and that no single computer controls it. Distinguish the Internet (the infrastructure) from the World Wide Web (one system of pages built on top of it).