D329 Networks and Security Applications - Set 1 - Part 1

Correct Answer: 7

The OSI model defines seven layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application.

Correct Answer: Network (Layer 3)

The Network layer handles logical addressing and routing, determining the path packets take between different networks.

Correct Answer: Data Link (Layer 2)

The Data Link layer uses MAC addresses for delivery between devices on the same physical network segment.

Correct Answer: Transport (Layer 4)

The Transport layer provides end-to-end delivery, segmentation, flow control, and, in the case of TCP, reliability through acknowledgments and retransmission.

Correct Answer: 4

The TCP/IP model has four layers: Network Access (Link), Internet, Transport, and Application, consolidating several OSI layers.

Correct Answer: TCP is connection-oriented and reliable; UDP is connectionless and best-effort

TCP establishes a connection and guarantees ordered, reliable delivery through acknowledgments. UDP sends datagrams without connection setup or delivery guarantees.

Correct Answer: UDP, because low latency matters more than perfect delivery

Streaming tolerates occasional lost frames but not delay, so UDP's low overhead and absence of retransmission suit it better than TCP.

Correct Answer: SYN, SYN-ACK, ACK

A TCP connection is established when the client sends SYN, the server replies SYN-ACK, and the client confirms with ACK.

Correct Answer: 80

HTTP uses TCP port 80 by default. HTTPS uses port 443, SSH uses 22, and SMTP uses 25.

Correct Answer: 443

HTTPS, which is HTTP secured with TLS, uses TCP port 443 by default.

Correct Answer: 22

SSH uses TCP port 22. Telnet, its insecure unencrypted predecessor, uses port 23.

Correct Answer: SSH encrypts the session while Telnet transmits in cleartext

Telnet sends all data including credentials in cleartext, allowing interception. SSH encrypts the entire session, protecting confidentiality and integrity.

Correct Answer: Resolution of domain names to IP addresses

The Domain Name System translates human-readable domain names into the numeric IP addresses needed to route traffic.

Correct Answer: 53

DNS uses port 53, typically over UDP for standard queries and over TCP for zone transfers or large responses.

Correct Answer: Automatically assigns IP configuration to hosts

The Dynamic Host Configuration Protocol automatically assigns IP addresses, subnet masks, gateways, and DNS servers to clients joining a network.

Correct Answer: Mapping an IP address to a MAC address on a local network

The Address Resolution Protocol discovers the MAC address associated with a known IP address on the local network segment.

Correct Answer: Sending forged ARP messages to associate an attacker's MAC with another host's IP

ARP spoofing sends falsified ARP replies so traffic destined for another host is sent to the attacker instead, enabling interception on the local segment.

Correct Answer: Diagnostic and error messages such as those used by ping

The Internet Control Message Protocol carries diagnostic and error information. Utilities such as ping and traceroute rely on it.

Correct Answer: Displaying the path packets take through intermediate routers

Traceroute reveals each router hop along the path to a destination by incrementing the TTL value, helping locate where connectivity fails.

Correct Answer: Packets circulating endlessly in a routing loop

Each router decrements the Time To Live value, discarding the packet when it reaches zero, which prevents packets from looping forever.