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Network Fundamentals — CCNA practice questions

Domain 1 of the Cisco CCNA (200-301) exam. 438 questions on this domain in the full bank — here are four free samples with answers and explanations.

Question 1 · Difficulty 2/5

Which device primarily forwards frames based on MAC addresses within a LAN?
  1. Layer 2 switch
  2. Router
  3. Firewall
  4. Load balancer
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Correct answer: A

Layer 2 switch
A Layer 2 switch forwards frames using a MAC address table learned from incoming frames. Routers (B) make forwarding decisions based on IP addresses. Firewalls (C) filter traffic based on security policies, often using ACLs. Load balancers (D) distribute application traffic across servers.

Question 2 · Difficulty 2/5

Which transport layer protocol provides connectionless communication and is the primary example emphasized in CCNA-level networking?
  1. TCP
  2. UDP
  3. SCTP
  4. IPsec
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Correct answer: B

UDP
UDP (User Datagram Protocol) is the connectionless transport layer protocol emphasized at the CCNA level; it sends datagrams without establishing a session or guaranteeing delivery, making it suitable for latency-sensitive applications like DNS, VoIP, and streaming. TCP, by contrast, is connection-oriented and uses a three-way handshake with acknowledgments. SCTP is a lesser-known transport protocol that is connection-oriented and supports multihoming, while IPsec operates at the network layer rather than the transport layer.

Question 3 · Difficulty 3/5

What is the broadcast address for the network 192.168.20.0/26?
  1. 192.168.20.63
  2. 192.168.20.62
  3. 192.168.20.64
  4. 192.168.20.0
Show answer & explanation

Correct answer: A

192.168.20.63
A /26 subnet mask is 255.255.255.192, giving 64 addresses per subnet. The first subnet ranges from 192.168.20.0 to 192.168.20.63. The broadcast address is the last address, 192.168.20.63. Valid hosts are .1 through .62. Option B is the last usable host, C is the next network, and D is the network address.

Question 4 · Difficulty 3/5

Which cable type uses light signals and is specifically designed for long-distance, high-bandwidth communication spanning several kilometers or more?
  1. UTP (Unshielded Twisted Pair)
  2. Coaxial
  3. Multimode fiber
  4. Single-mode fiber
Show answer & explanation

Correct answer: D

Single-mode fiber
Single-mode fiber uses a narrow core and laser light to transmit signals over long distances (typically tens of kilometers) with minimal attenuation and signal loss, making it ideal for high-bandwidth, long-haul communication. Multimode fiber also uses light signals but is limited to shorter distances (up to ~500 m) due to modal dispersion. UTP and coaxial cables are copper-based and cannot match the distance or bandwidth of single-mode fiber.

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