ICND1 Network Fundamentals & IP Addressing 2 — Questions and Answers
Question 1: Which subnet mask allows for 14 usable host addresses per subnet?
- /27
- /28 (Correct answer)
- /29
- /30
Correct answer: /28
A /28 mask leaves 4 host bits, yielding 2^4 - 2 = 14 usable host addresses.
Question 2: What is the broadcast address of the subnet 192.168.10.64/26?
- 192.168.10.127 (Correct answer)
- 192.168.10.128
- 192.168.10.126
- 192.168.10.191
Correct answer: 192.168.10.127
A /26 block size is 64; subnet 192.168.10.64 has broadcast at .127 (64+64-1).
Question 3: Which layer of the OSI model is responsible for logical addressing and routing?
- Layer 2 – Data Link
- Layer 3 – Network (Correct answer)
- Layer 4 – Transport
- Layer 1 – Physical
Correct answer: Layer 3 – Network
Layer 3 (Network) handles logical IP addressing and path determination via routing.
Question 4: A host has IP 172.16.45.200/20. What is the network address of this subnet?
- 172.16.32.0
- 172.16.40.0 (Correct answer)
- 172.16.45.0
- 172.16.48.0
Correct answer: 172.16.40.0
A /20 has a block size of 16 in the third octet; 32 ≤ 45 < 48, so the network is 172.16.40.0.
Question 5: Which protocol operates at Layer 2 and is used to map IP addresses to MAC addresses?
- RARP
- ICMP
- ARP (Correct answer)
- DHCP
Correct answer: ARP
ARP (Address Resolution Protocol) resolves known IP addresses to MAC addresses on the local segment.
Question 6: What is the valid host range for the subnet 10.0.0.128/25?
- 10.0.0.129 – 10.0.0.254 (Correct answer)
- 10.0.0.128 – 10.0.0.255
- 10.0.0.129 – 10.0.0.255
- 10.0.0.130 – 10.0.0.254
Correct answer: 10.0.0.129 – 10.0.0.254
Network = 10.0.0.128, broadcast = 10.0.0.255; valid hosts are .129 through .254.
Question 7: Which PDU name is used at the OSI Transport layer?
- Frame
- Packet
- Segment (Correct answer)
- Bit
Correct answer: Segment
The Transport layer (Layer 4) encapsulates data into segments.
ICND1 Network Fundamentals & IP Addressing 2
Which subnet mask allows for 14 usable host addresses per subnet?