Computer Networks and Internet Fundamentals
What the domain covers
Computer Networks and Internet Fundamentals tests how devices connect and exchange data, how the internet is addressed and named, and how common services such as the web and email work.
Core rules and concepts
- LAN covers a limited area; WAN spans large distances; MAN covers a city. The internet is a network of networks, while the World Wide Web is a service on it.
- Topologies include star, bus, ring, and mesh. Star is common in LANs because a failed node does not stop the whole network, though the central switch is a single point of failure.
- A hub repeats signals to all ports; a switch forwards frames by MAC address; a router forwards packets between networks by IP address.
- IPv4 addresses are 32-bit; IPv6 is 128-bit. A MAC address is a hardware identifier on a local link. DNS maps domain names to IP addresses.
- TCP is connection-oriented and reliable; UDP is connectionless and lower overhead. HTTP/HTTPS, SMTP, IMAP/POP3, and FTP are application-layer protocols.
- Bandwidth is capacity; latency is delay. More bandwidth does not reduce ping time.
Worked example
A user types https://www.example.com/page. The browser separates the scheme (https), host (www.example.com), and path (/page). It asks DNS for the host’s IP address, opens a TCP connection to port 443, negotiates TLS, and sends an HTTP request for /page. Reason: names are for humans; routers need IP addresses. HTTPS adds encryption and integrity through TLS, but it does not by itself prove that the site is honest.
Traps that cost marks
The internet is not the same as the web. HTTP is not encrypted; HTTPS is. A router does not normally replace a switch within one LAN. Do not confuse IP address with MAC address or bandwidth with latency. A secure padlock means the connection is encrypted, not that the content is trustworthy. Email delivery uses SMTP; retrieval uses IMAP or POP3.