ICND1 Network Fundamentals & IP Addressing 4 — Questions and Answers
Question 1: Which IPv4 address range is reserved for multicast?
- 192.168.0.0 – 192.168.255.255
- 224.0.0.0 – 239.255.255.255 (Correct answer)
- 240.0.0.0 – 255.255.255.254
- 169.254.0.0 – 169.254.255.255
Correct answer: 224.0.0.0 – 239.255.255.255
Class D addresses (224.0.0.0–239.255.255.255) are reserved for multicast group communication.
Question 2: A network administrator needs at least 50 subnets from 10.0.0.0/8. What is the minimum number of bits to borrow?
- 5
- 6 (Correct answer)
- 7
- 8
Correct answer: 6
2^6 = 64 ≥ 50 subnets; borrowing 5 bits only yields 32, which is insufficient.
Question 3: Which statement correctly describes full-duplex Ethernet operation?
- Devices can send and receive simultaneously, eliminating collisions (Correct answer)
- Devices share bandwidth using CSMA/CD
- Only one device transmits at a time on the segment
- Full-duplex requires a hub to coordinate transmissions
Correct answer: Devices can send and receive simultaneously, eliminating collisions
Full-duplex allows simultaneous send and receive by using separate wire pairs, eliminating collision domains.
Question 4: What is the CIDR notation for the subnet mask 255.255.255.192?
- /25
- /26 (Correct answer)
- /27
- /28
Correct answer: /26
255.255.255.192 = 11111111.11111111.11111111.11000000, which has 26 contiguous 1-bits.
Question 5: Which private IP address range is defined by RFC 1918 for Class A networks?
- 10.0.0.0 – 10.255.255.255 (Correct answer)
- 172.16.0.0 – 172.31.255.255
- 192.168.0.0 – 192.168.255.255
- 127.0.0.0 – 127.255.255.255
Correct answer: 10.0.0.0 – 10.255.255.255
RFC 1918 designates 10.0.0.0/8 as the private Class A range.
Question 6: At which OSI layer does a switch make forwarding decisions based on MAC addresses?
- Layer 1
- Layer 2 (Correct answer)
- Layer 3
- Layer 4
Correct answer: Layer 2
Switches use MAC address tables at Layer 2 (Data Link) to forward frames out the correct port.
Question 7: Which address is 127.0.0.1 used for?
- Default gateway
- DNS server
- Loopback / localhost testing (Correct answer)
- Broadcast on all interfaces
Correct answer: Loopback / localhost testing
127.0.0.1 is the loopback address used to test the TCP/IP stack on the local host without sending traffic to the network.
ICND1 Network Fundamentals & IP Addressing 4
Which IPv4 address range is reserved for multicast?