Computer Networks and the Internet
What the exam tests
Networks connect devices to share data and resources. The exam covers LANs and WANs, topologies, media, the TCP/IP model, IP addressing, DNS, HTTP/HTTPS, packet switching and basic performance terms.
Core rules
- A LAN covers a limited area and is usually privately managed; a WAN spans larger distances and often uses carrier links. The internet is a global network of networks.
- Packet switching splits messages into packets that are routed independently and reassembled at the destination; this is robust but can cause variable delay.
- IP addresses identify interfaces for routing; MAC addresses identify network interfaces on a local link. Private IPv4 addresses are not routed on the public internet.
- DNS resolves domain names to IP addresses. HTTP transfers web content; HTTPS adds TLS encryption and server authentication.
Worked example
For 192.168.10.0/24, the /24 means 24 network bits and 8 host bits. Total addresses = 2^8 = 256. The network address is 192.168.10.0 and the broadcast address is 192.168.10.255, leaving 254 usable host addresses. Reasoning: two addresses are reserved for network and broadcast; a host cannot use them.
Traps that cost marks
Do not confuse an IP address with a MAC address. A hub broadcasts to all ports; a switch forwards frames using MAC addresses. Bandwidth is capacity, throughput is actual achieved rate, and latency is delay. Do not say HTTPS makes a website trustworthy; it secures the connection. Do not treat DNS as a routing protocol.
Exam focus
Expect topology comparisons, protocol-purpose matching and simple subnet or address-count calculations.