ICT Networking Models and Protocols 3 — Questions and Answers
Question 1: What does the acronym 'PDU' stand for in networking?
- Protocol Data Unit (Correct answer)
- Packet Delivery Unit
- Physical Data Upload
- Primary Distribution Utility
Correct answer: Protocol Data Unit
PDU stands for Protocol Data Unit, the generic term for data at each OSI layer (e.g., segment at Transport, packet at Network, frame at Data Link).
Question 2: Which protocol is used to automatically assign IP addresses to devices on a network?
- DNS
- DHCP (Correct answer)
- ARP
- ICMP
Correct answer: DHCP
DHCP (Dynamic Host Configuration Protocol) automatically assigns IP addresses, subnet masks, default gateways, and DNS server addresses to clients.
Question 3: The three-way handshake used by TCP involves which sequence of messages?
- SYN → ACK → FIN
- SYN → SYN-ACK → ACK (Correct answer)
- ACK → SYN → FIN
- SYN → FIN → ACK
Correct answer: SYN → SYN-ACK → ACK
TCP establishes a connection with SYN from client, SYN-ACK from server, then ACK from client — a three-way handshake.
Question 4: Which OSI layer adds a MAC address header to data, creating a frame?
- Physical layer
- Data Link layer (Correct answer)
- Network layer
- Transport layer
Correct answer: Data Link layer
The Data Link layer (Layer 2) encapsulates packets into frames and adds source and destination MAC addresses.
Question 5: In IPv4, what is the purpose of the subnet mask?
- To encrypt IP packets during transmission
- To identify the network and host portions of an IP address (Correct answer)
- To route packets to the default gateway
- To convert domain names to IP addresses
Correct answer: To identify the network and host portions of an IP address
A subnet mask distinguishes the network portion from the host portion of an IPv4 address, enabling proper routing decisions.
Question 6: Which protocol resolves IP addresses to MAC addresses on a local network segment?
- DNS
- DHCP
- ARP (Correct answer)
- RARP
Correct answer: ARP
ARP (Address Resolution Protocol) broadcasts a request on the local segment to discover the MAC address associated with a known IP address.
Question 7: A user can ping a server by IP address but not by hostname. Which protocol is most likely failing?
- ARP
- DHCP
- DNS (Correct answer)
- ICMP
Correct answer: DNS
DNS (Domain Name System) resolves hostnames to IP addresses; if ping by IP works but hostname fails, DNS resolution is the issue.
ICT Networking Models and Protocols 3
What does the acronym 'PDU' stand for in networking?