Sample Cisco CCNA 200-301 Practice Questions
Q: Which layer of the OSI model is responsible for logical addressing and routing?
A: Network (Layer 3) — The Network layer (Layer 3) handles logical addressing (IP addresses) and routing packets between networks. The Data Link layer handles physical addressing (MAC). The Transport layer manages end-to-end communication.
Q: What is the default VLAN on a Cisco switch that all ports belong to initially?
A: VLAN 1 — On Cisco switches, VLAN 1 is the default VLAN. All switch ports are members of VLAN 1 by default. VLAN 1 cannot be deleted or renamed. VLANs 1002-1005 are reserved for legacy Token Ring and FDDI.
Q: Which type of route is manually configured by a network administrator?
A: Static route — A static route is manually configured by an administrator using the 'ip route' command. Connected routes are automatically added when an interface is configured with an IP address and brought up. Dynamic routes are learned through routing protocols.
Q: What is the purpose of a DHCP relay agent?
A: To forward DHCP broadcast requests to a DHCP server on a different subnet — A DHCP relay agent (configured with 'ip helper-address') forwards DHCP broadcast requests from clients to a DHCP server located on a different subnet. Without a relay, DHCP broadcasts cannot cross router boundaries.
Q: What do the three components of the CIA triad stand for?
A: Confidentiality, Integrity, Availability — The CIA triad stands for Confidentiality (data is accessible only to authorized users), Integrity (data is accurate and unaltered), and Availability (systems and data are accessible when needed). It is the foundation of information security.
Q: What does REST stand for in the context of APIs?
A: Representational State Transfer — REST (Representational State Transfer) is an architectural style for APIs that uses standard HTTP methods (GET, POST, PUT, DELETE) and typically returns data in JSON or XML format. RESTful APIs are stateless and resource-based.
Q: Which OSI layer is responsible for establishing, managing, and terminating sessions between applications?
A: Session (Layer 5) — The Session layer (Layer 5) manages sessions (dialogs) between applications, including establishment, maintenance, and teardown. The Presentation layer handles data formatting, and the Transport layer handles end-to-end delivery.
Q: A network engineer is troubleshooting and discovers a CRC error on received frames. At which OSI layer does this issue occur?
A: Data Link (Layer 2) — CRC (Cyclic Redundancy Check) is a frame check sequence computed at the Data Link layer (Layer 2). CRC errors indicate corrupted frames, which are detected by the receiving NIC at Layer 2.
Q: What is the default subnet mask for a Class B IPv4 address?
A: 255.255.0.0 — Class B addresses (128.0.0.0 to 191.255.255.255) have a default subnet mask of 255.255.0.0 (/16). Class A uses 255.0.0.0 (/8) and Class C uses 255.255.255.0 (/24).
Q: How many usable host addresses are available in a /26 IPv4 subnet?
A: 62 — A /26 subnet has 6 host bits, giving 2^6 = 64 total addresses. Subtract 2 for the network and broadcast addresses, leaving 62 usable host addresses.