Top 20 CCNA Interview Questions & Answers for Beginners
Sep 6, 2025
Cisco Certified Network Associate – Entry-Level Interview Guide
CCNA (Cisco Certified Network Associate) is a certification that proves your ability to understand, use, and manage Cisco networks. The CCNA certification provides you with the skills necessary for optimizing and administering Cisco networking resources in an organization. With this credential, you can move on to higher-level certifications such as the MCSA or MCDBA. Obtaining CCNA certification improves your knowledge base and enhances your job prospects.
Here are some important questions which can help you
1. What are the port types on a network switch?
There are two general types of switch ports:
Access Ports: Access ports are employed for the connection of endpoint devices such as PCs to a single VLAN. They support only untagged traffic and are suitable for straightforward LAN configurations.
Combo Ports: Available on some high-end Cisco switches, a combo port provides both a copper (RJ45) and a fiber (SFP) interface—one at a time. It provides flexibility based on network media needs.
2. Describe the three types of data transmission.
Data can be transmitted by the following methods:
Simplex: Communication in one direction only, such as a broadcast television signal.
Half-Duplex: Data goes both ways but not at the same time. Devices alternate sending or receiving.
Full-Duplex: Both devices can send and receive data simultaneously, allowing for quicker communication. This is prevalent in current Ethernet networks.
3. Enumerate and describe various kinds of IPX access lists.
Standard Access List: Filters only on the source IP address. It is the simplest type of ACL.
Extended Access List: Source/destination IP, port numbers, and types of protocols such as TCP or UDP-based filters.
Reflexive Access List: Dynamic ACLs that permit return traffic only if initiated from within the network, providing an added level of security.
4. What is 100BaseFX?
100BaseFX is a fiber-optic Ethernet specification for sending data at 100 Mbps. It employs two optical fibers, one to send and the other to receive. It is less susceptible to electromagnetic interference than copper-based methods and is ideal for longer-distance communications.
5. What switching technique is employed in the Cisco Catalyst 5000 series?
The Cisco Catalyst 5000 switches employ the Store-and-Forward switching mechanism. This approach reads the frame into memory, makes an error check through a CRC check, and passes it on only if it is valid. This makes for very high data accuracy, although with somewhat higher latency.
6. What kinds of memory are used in Cisco routers?
RAM (Random Access Memory): Holds current configuration and routing tables. Data is lost when rebooted.
NVRAM (Non-Volatile RAM): Saves the startup configuration file and holds data even without power.
ROM (Read-Only Memory): Holds boot instructions and the minimal diagnostic software.
Flash Memory: Stores the Cisco IOS operating system image and provides for software upgrades.
7. How are traceroute and tracert different?
Traceroute: Used in Unix/Linux/macOS, usually sends UDP packets.
Tracert: Windows equivalent, sends ICMP Echo Requests.
Both utilities map out the path packets follow to a destination IP by continuously increasing the TTL (Time-To-Live) and logging every hop.
8. What is a DLCI in Frame Relay networks?
DLCI (Data Link Connection Identifier) is a special number utilized in Frame Relay networks to identify unique virtual circuits. Every circuit is assigned its own DLCI to assist routers and switches in directing traffic correctly.
9. Which commands are utilized to show RAM and NVRAM content on a router?
RAM Content: Utilize show running-config to view the active configuration in memory.
NVRAM Content: Utilize show startup-config to view the stored configuration loaded during boot-up.
10. Define Frame Relay.
Frame Relay is a Layer 2 WAN protocol used for the transmission of variable-length packets across virtual circuits. It's both efficient and has low overhead. While obsolete to a large extent these days, it was widely employed to link LANs across long distances.
11. How does User EXEC mode differ from Privileged EXEC mode in Cisco devices?
User EXEC Mode (>): Restricted access; only basic monitoring commands such as ping and show.
Privileged EXEC Mode (#): Provides complete access to configuration and debugging capabilities. You enter this mode with the enable command.
12. What is EIGRP and what metrics does it use to determine the best path?
EIGRP (Enhanced Interior Gateway Routing Protocol) is a Cisco-specific routing protocol that offers high convergence speed and scalable performance.
Metrics taken into account are:
Bandwidth
Delay
Load
Reliability
MTU (applied only in case of tie-breaking)
EIGRP employs the DUAL algorithm in order to identify loop-free paths in an efficient manner.
13. What is CDP in Cisco networking?
Cisco Discovery Protocol (CDP) is an internal Cisco Layer 2 protocol used to discover directly connected Cisco devices. It assists network administrators in discovering neighbor devices and their interfaces, IP addresses, and hardware types.
Command to use: show cdp neighbors
14. What is the difference between a broadcast domain and a collision domain?
Type | Explanation |
|---|---|
Broadcast Domain | A collection of devices to which each can broadcast from the other. Broadcast domains are segmented by routers and VLANs. |
Collision Domain | An area of the network where packet collisions take place. Collision domains are isolated by switch ports, enhancing performance. |
15. What is Route Poisoning?
Route poisoning is employed by routing protocols such as RIP to avoid loops. On finding an invalid route, a router advertises the route with an unreachable metric (typically 16 in RIP), thereby "poisoning" it and stopping others from using it.
16. Which passwords are used within Cisco routers?
Console Password: Protects console port physical access.
VTY Password: Secures Telnet or SSH remote access.
Enable Password: allows privileged mode access; plain-text.
Enable Secret: an encrypted password and supersedes the enable password.
17. Public vs. Private IP addresses.
Public IP: routable on the internet and allocated by your ISP.
Private IP: used locally in a network; has to be translated by NAT to hit the internet.
Private IP ranges:
192.168.0.0 – 192.168.255.255
10.0.0.0 – 10.255.255.255
172.16.0.0 – 172.31.255.255
18. What is PoE (Power over Ethernet)?
PoE technology allows Ethernet cables to supply power and data to devices like IP phones, security cameras, and wireless access points. This does away with the necessity for independent electrical cabling, making it easy to install in remote or high-ceiling locations.
19. What is Round Trip Time (RTT)?
RTT is the time it takes for a packet of data to travel from sender to receiver and vice versa. It's an important network performance indicator that shows latency. The lower RTT, the faster the communication.
20. What is a DHCP Scope
A DHCP scope specifies a range of IP addresses to be leased out by a DHCP server to clients. It also contains information such as subnet mask, lease duration, default gateway, and DNS servers. Scopes provide dynamic and automatic management of IP addresses in a network.
