ICND1 Network Fundamentals & IP Addressing 5 — Questions and Answers
Question 1: What is the number of usable host addresses in a /30 subnet?
- 2 (Correct answer)
- 4
- 6
- 8
Correct answer: 2
A /30 leaves 2 host bits: 2^2 - 2 = 2 usable hosts, making it ideal for point-to-point WAN links.
Question 2: Which encapsulation type is used by default on a Cisco serial interface running HDLC?
- PPP
- Frame Relay
- Cisco HDLC (Correct answer)
- SLIP
Correct answer: Cisco HDLC
Cisco serial interfaces default to Cisco's proprietary HDLC encapsulation, which differs from the ISO HDLC standard.
Question 3: A host sends a packet to 255.255.255.255. What kind of message is this?
- Directed broadcast
- Multicast
- Unicast
- Limited broadcast (Correct answer)
Correct answer: Limited broadcast
255.255.255.255 is the limited broadcast address, delivered to all hosts on the local network segment only.
Question 4: In the OSI model, which layer handles the conversion of data formats such as encryption and compression?
- Application
- Session
- Presentation (Correct answer)
- Transport
Correct answer: Presentation
The Presentation layer (Layer 6) translates data formats, handles encryption/decryption, and compression.
Question 5: Which network address belongs to the same /27 subnet as host 192.168.5.100?
- 192.168.5.64
- 192.168.5.96 (Correct answer)
- 192.168.5.112
- 192.168.5.128
Correct answer: 192.168.5.96
A /27 has a block size of 32; 96 ≤ 100 < 128, so the network address is 192.168.5.96.
Question 6: Which statement is true about CSMA/CD?
- It is used in token ring networks to prevent collisions
- It detects collisions after they occur and retransmits after a random back-off (Correct answer)
- It prevents all collisions by scheduling transmissions
- It is used exclusively in wireless networks
Correct answer: It detects collisions after they occur and retransmits after a random back-off
CSMA/CD (Carrier Sense Multiple Access/Collision Detection) detects collisions and uses a random back-off timer before retransmitting.
Question 7: What does the term 'default gateway' refer to in IP networking?
- The IP address of the local DNS server
- The router interface used to reach networks outside the local subnet (Correct answer)
- The switch that connects hosts to the LAN
- The IP address assigned to the DHCP server
Correct answer: The router interface used to reach networks outside the local subnet
The default gateway is the router interface that hosts send packets to when the destination is not on the local subnet.
ICND1 Network Fundamentals & IP Addressing 5
What is the number of usable host addresses in a /30 subnet?