ACA Networking Fundamentals 2 — Questions and Answers
Question 1: Which layer of the OSI model is responsible for logical addressing and routing packets between networks?
- Data Link
- Network (Correct answer)
- Transport
- Session
Correct answer: Network
The Network layer (Layer 3) handles logical IP addressing and determines the best path for packets across interconnected networks.
Question 2: What is the default subnet mask for a Class B IP address?
- 255.0.0.0
- 255.255.0.0 (Correct answer)
- 255.255.255.0
- 255.255.255.128
Correct answer: 255.255.0.0
Class B addresses use a default subnet mask of 255.255.0.0 (/16), covering the range 128.0.0.0 to 191.255.255.255.
Question 3: Which protocol resolves IP addresses to MAC addresses on a local network segment?
- RARP
- DNS
- ARP (Correct answer)
- DHCP
Correct answer: ARP
ARP (Address Resolution Protocol) maps a known IPv4 address to its corresponding MAC address by broadcasting a request on the local segment.
Question 4: What is the maximum number of usable host addresses in a /28 subnet?
- 14 (Correct answer)
- 16
- 30
- 62
Correct answer: 14
A /28 subnet has 16 total addresses; subtracting the network and broadcast addresses leaves 14 usable host addresses.
Question 5: Which transmission mode allows data to flow in both directions simultaneously?
- Simplex
- Half-duplex
- Full-duplex (Correct answer)
- Multiplex
Correct answer: Full-duplex
Full-duplex allows simultaneous bidirectional communication, effectively doubling throughput compared to half-duplex on the same link.
Question 6: At which OSI layer does a standard Layer 2 switch make its forwarding decisions?
- Layer 1 – Physical
- Layer 2 – Data Link (Correct answer)
- Layer 3 – Network
- Layer 4 – Transport
Correct answer: Layer 2 – Data Link
A Layer 2 switch reads the destination MAC address in the Ethernet frame header to decide which port to forward the frame out of.
Question 7: Which IPv6 address type is equivalent to the IPv4 private address range and is used only within a local network?
- Global Unicast
- Loopback
- Link-Local (Correct answer)
- Anycast
Correct answer: Link-Local
Link-local addresses (FE80::/10) are automatically assigned to every IPv6-enabled interface and are only valid within the local link.
ACA Networking Fundamentals 2
Which layer of the OSI model is responsible for logical addressing and routing packets between networks?