Networks: Architecture, Protocols and Security
What the exam tests
Networks tests how data moves between devices and how that movement is secured. Questions cover network types and topologies, hardware, protocols and layers, IP addressing, packet switching, and threats and countermeasures.
Core rules
- LAN covers a small area; WAN spans larger distances; VLAN logically segments a LAN; VPN creates an encrypted tunnel over a public network.
- A hub repeats bits to all ports; a switch forwards frames by MAC address; a router forwards packets between networks by IP address; a gateway translates between protocols.
- TCP is connection-oriented and reliable; UDP is connectionless with lower overhead. DNS resolves names, DHCP leases addresses, HTTP/HTTPS transfer web content, SMTP/POP3/IMAP handle mail.
- Packet switching splits data into packets that may take different routes and are reassembled at the destination.
- Security: firewalls filter traffic, encryption protects confidentiality, authentication verifies identity, and WPA2/WPA3 protect wireless traffic; WEP is obsolete.
Worked example
A client requests https://school.example. DNS resolves the name to an IP address; the client opens a TCP connection to port 443 and negotiates TLS; HTTP requests and responses travel in packets routed by routers. Reasoning: HTTPS protects content in transit, but DNS may still reveal the domain unless encrypted DNS is used, and the server must present a trusted certificate.
Traps
Saying a switch routes between networks; confusing TCP with HTTP; placing encryption only at the application layer; assuming HTTPS hides the destination IP; forgetting that a firewall cannot remove malware already inside; mixing OSI layers.