2023's Top CCNA Interview Questions - Your Ultimate Guide to Acing the Interview, brought to you by IQCode.

Overview of CCNA Certification and Interview Questions for Freshers

CCNA (Cisco Certified Network Associate) is an IT certification offered by Cisco, a globally renowned company for manufacturing and selling networking equipment. This certification validates the general ability of an individual to install, configure, operate, and troubleshoot switched and routed networks within an enterprise. It offers intricate knowledge and understanding of networking concepts that are crucial for honing one's networking skills and is considered as the foundational certification in the networking domain. Cisco Systems' CCNA and CCNP certifications are regarded as the most preferred certifications in networking, highly sought by topmost IT companies.

One advantage of being CCNA certified is that it opens up numerous job opportunities in various top IT companies. To assist those preparing for CCNA interviews, we have compiled some commonly asked interview questions, especially for freshers.

CCNA Interview Questions for Freshers:

1. Can you explain Routing?

Answer: Routing can be defined as the process of transferring data packets across different networks using routers. In routing, the router finds the most optimal path for data transmission by comparing the available paths that a particular data packet can take to reach its destination. There are two types of routing- Static and Dynamic routing. Static routing is manually configured and involves the administrator defining the path data packets will take. On the other hand, dynamic routing is configured using routing protocols like OSPF (Open Shortest Path First) or EIGRP (Enhanced Interior Gateway Routing Protocol), which automate the process of finding the shortest path for data transmission.

Meaning of Data Packets

Data packets refer to units of data that are transmitted through a network. In computer networking, data is transmitted in small data packets, each containing a part of the overall message being sent. These packets contain not only the data being transmitted, but also the necessary information to route the data to its intended destination. Data packets are used to efficiently transmit large amounts of data over a network while ensuring that the data is transmitted accurately and reliably.

Routers and Their Major Functions

In computer networking, a router is a device that connects multiple networks together and forwards data packets between them. The main functions of a router include:

• Directing network traffic towards its intended destination
• Filtering out unwanted network traffic
• Converting network data from one format to another as necessary
• Providing security by controlling access to the network
• Managing network congestion to ensure efficient data flow

Routers are a critical component in enabling internet connectivity and communication between different devices and networks. They play a vital role in ensuring that data reaches its intended destination securely and efficiently.

// Example of a basic router setup in JavaScript

const express = require('express');
const router = express.Router();

router.get('/', (req, res) => {
  // Perform actions for home page request
});

router.post('/submit', (req, res) => {
  // Perform actions for form submission request
});

module.exports = router;

Types of Routes Available in Routers

In routers, there are several types of routes available:

• Static Routes
• Dynamic Routes
• Default Routes
• Host Routes
• Floating Routes
• Policy-Based Routes

Static routes are configured by a network administrator and do not change until the administrator modifies them. Dynamic routes are learned automatically by the router through a routing protocol and can change based on network topology changes. Default routes are used for forwarding traffic when no other route matches the destination. Host routes are used to specify a specific host rather than an entire network. Floating routes are backup routes that are used when the primary path is unavailable. Policy-based routes are configured based on specific criteria, such as the source IP address or application type.

Meaning of Switching

Switching refers to the process of changing from one thing to another. In technology, switching usually involves transferring data or information from one source to another. In networking, switching is the process of forwarding data packets between nodes in a computer network. Switching is also used in telecommunication to refer to the process of routing calls or messages from one network to another.

Types of Switch Ports

In networking, switches have different types of ports that are used to connect devices. Two common types of switch ports are:

1. Access ports: These ports are used to connect end devices, such as computers and printers, to the switch. 2. Trunk ports: These ports are used to connect switches to each other, allowing them to communicate and share VLAN information.

IPX Access List Names

To create unique IPX access list names, you can consider using descriptive names that reflect the purpose or function of the access list. Here are some examples:

- ipx_acl_marketing - ipx_acl_sales - ipx_acl_hr - ipx_acl_accounting - ipx_acl_helpdesk

Remember to choose a name that is easy to understand and remember for future reference.

Main Objectives of Data Link Layer and Transport Layer

The main objective of the Data Link Layer is to provide error-free and reliable communication over the physical layer. It performs functions such as framing, error control and flow control. Its main focus is to ensure that data is transmitted accurately and efficiently between two adjacent network nodes.

The main objective of the Transport Layer is to provide end-to-end error-free and reliable communication between two processes or applications in different network devices. It offers services such as segmentation, reassembly, acknowledgement, congestion control and reliable data transfer. Its main focus is to ensure that data is transmitted in its entirety and delivered to the intended destination without loss or duplication.

Understanding 100BASEFX

100BASEFX is a type of Fast Ethernet technology that uses optical fiber cables to transmit data at a rate of 100 Mbps. It is a popular networking standard used in LANs (Local Area Networks) for high-speed data transfer and communication between devices. In contrast to 100BASE-T, which uses twisted-pair copper cables, 100BASEFX employs multimode or single-mode fiber optic cables that transmit data using light waves. This allows for longer cable distances without suffering from electromagnetic interference common with copper cables.

LAN Switching Method Used in Cisco Catalyst 5000

In Cisco Catalyst 5000, the most commonly used LAN switching method is the Virtual LAN (VLAN) switching method.

Types of Memories Used in Cisco Routers

Cisco routers make use of several types of memory to operate efficiently. The different types are as follows:

1. Flash memory

Flash memory is non-volatile memory that stores the Cisco IOS software image, as well as other system-related files and configurations.

2. RAM

Random Access Memory (RAM) is used as a temporary workspace for the router and stores the running configuration data, routing tables, and ARP cache.

3. NVRAM

Non-volatile RAM (NVRAM) is used to store the startup configuration, which is loaded into RAM during boot-up.

4. ROM

Read-Only Memory (ROM) contains the firmware for the router's bootup process and performs diagnostic tests on hardware components.

By utilizing these different types of memory, Cisco routers are able to perform their functions effectively and reliably.

Differences between tracert and traceroute

Tracert and traceroute are two networking commands used to trace the route taken by packets of data sent over a network. The main differences between these two commands are:

1. OS Compatibility: Tracert is a Windows command, while traceroute is used in Unix-based operating systems.

2. Syntax: The syntax for tracert and traceroute is slightly different. For example, in tracert, you enter the destination IP address or website name after the command, while in traceroute, you enter the destination IP address or website name before the command.

3. Output: Tracert and traceroute produce slightly different output. Tracert displays the number of hops, IP addresses, and round trip times for packets sent between the source and destination. Traceroute displays the number of hops, IP addresses, and round trip times, along with other information, such as the time taken for each hop and the name of the router at each hop.

4. Time to Live (TTL): The default time to live value is different for tracert and traceroute. Tracert uses a TTL value of 128, while traceroute uses a TTL value of 64. The TTL value determines the maximum number of routers a packet can pass through before being discarded.

5. Packet Type: Tracert sends ICMP packets by default, while traceroute sends UDP packets with a specific port number.

In summary, while both tracert and traceroute are used to trace the route of packets over a network, they differ in their syntax, output, default TTL values, and type of packets sent.

Understanding DLCI

DLCI stands for Data Link Connection Identifier. It is a unique identifier used in Frame Relay networks to distinguish between multiple virtual circuits. Each DLCI is assigned to a specific virtual circuit by the service provider. The DLCI is used by the network to forward frames between devices across the virtual circuit.

Command to display RAM and NVRAM content

show startup-config

command can be used to display the NVRAM content.

show running-config

command can be used to display the RAM content.

Understanding Frame Relay

Frame Relay is a WAN technology that allows communication between local area networks (LANs) and between end devices over a shared communication network. It operates on layer 2 of the OSI (Open Systems Interconnection) model, which means it focuses on the data link layer. In simple terms, Frame Relay ensures the efficient transmission of data packets over a WAN by using a dedicated connection called a virtual circuit (VC) that enables data transfer at high speeds.

Three Possible Ways of Data Transmission in CCNA

In CCNA, there are three possible ways of data transmission:

1. Unicast - This is a point-to-point transmission where data is sent from one device to another device.
2. Broadcast - This is a one-to-all transmission where data is sent from one device to all devices on the network.
3. Multicast - This is a one-to-many transmission where data is sent from one device to a specific group of devices.

These three modes of data transmission are fundamental concepts in networking and are important to understand when working with CCNA.

Explanation of MTU

MTU stands for Maximum Transmission Unit. It refers to the maximum size of data that can be transmitted in a single network packet. It varies based on the type of network and communication protocol being used. In general, larger MTUs can result in better network efficiency and performance, but may also lead to more fragmentation and retransmission of packets in case of errors.

Types of Cables Used in Routing

In routing, different types of cables can be used to interconnect network devices. Some commonly used cables are:

- Ethernet Cable: Used to connect devices within a local area network (LAN) - Coaxial Cable: Used for cable television and cable modem connections - Fiber Optic Cable: Used for high-speed data transfer over long distances - Serial Cable: Used for connecting routers and switches for management purposes - Console Cable: Used for accessing the command-line interface of routers and switches

Explaining Network Latency

Network latency

refers to the delay or lag that occurs when data is transmitted between devices over a network. It is measured in milliseconds (ms) and is dependent on several factors, including the distance between the devices, the quality of the network infrastructure, and the amount of traffic on the network.

When data is transmitted, it travels over multiple devices and networks, which can cause delays in transmission. These delays add up, resulting in network latency. Latency can cause issues in real-time applications, such as video conferencing or online gaming, as it results in poor performance and can lead to lag, stuttering, or freezing.

Reducing network latency is important in ensuring smooth and responsive network performance. Techniques such as caching, content delivery networks (CDNs), and reducing the distance between devices can help minimize latency and optimize network speed.

Definition of User Mode and Privileged Mode

User Mode and Privileged Mode are two different modes of operation in a computer's operating system that define the level of access a program or user has to the system's resources.

User Mode is a restricted mode of operation in which programs or processes are executed with limited access to the system's resources. In User Mode, programs can only access a subset of the computer's available resources, such as the memory and CPU time allocated to them.

Privileged Mode, also known as Kernel Mode, is a higher-level mode of operation that provides programs with full access to the computer's resources. In this mode, programs or processes can access all system resources and perform privileged operations, such as modifying the kernel or accessing hardware directly.

Generally, only the operating system and device drivers run in privileged mode, while user applications run in user mode. This separation helps ensure the stability, security, and reliability of the system.

    // Example code in C showing a simple way to switch between user and privileged mode

    // switch to privileged mode
    asm("movl %eax, %cr0"); // set highest bit of the control register to 1
    
    // switch back to user mode
    asm("movl %eax, %cr0"); // set highest bit of the control register to 0

Understanding "Windows" in Networking

In networking, "Windows" refers to the Microsoft Windows operating system and its built-in networking capabilities. Windows computers can be configured to connect to a local area network (LAN) or a wide area network (WAN) using various networking protocols such as TCP/IP, FTP, and SMB. The Windows operating system includes tools and features such as the Command Prompt, Task Manager, and Network Connections that allow users to manage and troubleshoot networking issues. Additionally, Windows includes a variety of security features such as firewalls and antivirus software to protect the network from external threats.

Understanding the LLC Sublayer Function

The LLC (Logical Link Control) sublayer is a part of the Data Link Layer in the OSI (Open Systems Interconnection) model. It serves as an intermediate layer between the Media Access Control (MAC) layer and the Network Layer. The LLC sublayer has two primary functions, namely providing a seamless connection between the upper and lower layers and facilitating error-free data transmission. It achieves these functions by performing various operations such as error control, flow control, and addressing. The LLC sublayer is responsible for ensuring that data packets are transmitted reliably and efficiently between network devices, enhancing the overall performance of the network.

CCNA Interview Questions for Experienced

Question 24: Can you explain what EIGRP is? Could you also provide some examples of metrics used by the EIGRP protocol?

Answer:

Enhanced Interior Gateway Routing Protocol (EIGRP)

is an advanced distance-vector routing protocol that is used for IP networks. It enables routers to share information with one another, which helps to determine the fastest and most reliable path for routing data packets.

Some examples of the metrics used by EIGRP protocol include:

- Bandwidth - Delay - Load - Reliability - MTU (Maximum Transmission Unit)

These metrics help EIGRP protocol in determining the best path.

What is CDP? Write its functions.

CDP stands for Cisco Discovery Protocol which is a network protocol primarily used for network devices to share information about other directly connected devices. Here are some of the functions of CDP:

1. Device Discovery: In a network infrastructure that uses Cisco devices, CDP helps in discovering directly connected neighboring devices. It provides information about the devices such as their IP addresses and IOS versions, which help network administrators to locate and troubleshoot the devices.

2. Topology Mapping: CDP provides information about the physical connections between devices, enabling network administrators to create network topology maps.

3. VLAN Trunking: CDP helps in negotiating VLAN trunks between two Cisco networking devices. It provides information about the VLANs that are allowed through the trunk, allowing for automatic VLAN configuration.

4. Access Point (AP) Discovery: CDP helps in discovering Cisco Wireless Access Points (WAP) connected to a wired network. It provides information about the APs, such as their name and IP address, allowing for configuration and troubleshooting.

5. Voice over IP (VoIP): CDP helps in detecting Cisco IP phones connected to a network. It provides important information, such as phone model and firmware version, which allows the network to provide the appropriate amount of Power over Ethernet (PoE) to function.

Overall, CDP helps in simplifying network management by providing information about Cisco devices and their connectivity with other devices in the same network.

VLANs: Definition and Main Objective

In computer networking, VLAN stands for Virtual Local Area Network. It is a method of logically dividing a physical network into multiple, smaller virtual networks. Each VLAN operates as a separate network, even though devices within the VLAN may physically be connected to the same switch.

The main objective of VLAN is to improve network security, scalability, and flexibility. By separating network traffic into different VLANs, administrators can control access to sensitive resources, reduce the broadcast traffic on the network, and apply specific policies to different types of traffic. VLANs also enable more efficient use of network resources by allowing multiple logical networks to share the same physical infrastructure.

Benefits of Using VLANs

VLANs, or Virtual Local Area Networks, provide several benefits in network management:

- Enhanced network security: VLANs enable network administrators to group users and resources with similar security requirements into virtual LANs, reducing the risk of unauthorized access and potential security breaches. - Efficient use of network resources: By segmenting the network into VLANs, network traffic can be separated, making it easier to manage and reducing the risk of congestion. - Improved network performance: VLANs enable administrators to prioritize traffic according to its importance, ensuring that critical applications get the bandwidth they need. - Scalability: VLANs enable networks to be easily expanded or reconfigured without the need for physical reconfiguration of the network infrastructure. - Cost-effectiveness: VLANs reduce the need for additional network hardware by allowing multiple VLANs to share the same physical network infrastructure.

Overall, VLANs provide a flexible and efficient way to manage networks while enhancing security and performance.

Explanation of Broadcast Domains and Collision Domains

In networking, a broadcast domain refers to a logical division of a computer network, in which all nodes can broadcast messages to each other. This includes all devices that are connected to the same switch, hub, or any other networking equipment that allows for the broadcasting of messages. A broadcast message is a packet that is sent to all node addresses in a particular broadcast domain.

On the other hand, a collision domain is a physical division of a computer network in which packets can collide with one another, resulting in data loss and retransmission. This occurs in shared media, such as a hub or an Ethernet cable that two devices are connected to. When two devices transmit data simultaneously, a collision may occur, and both devices need to retransmit the data.

Understanding these domains is critical when designing a network, as their characteristics can affect network performance and security. By properly segmenting a network into different broadcast domains and collision domains, network administrators can control the flow of network traffic and minimize collision rates, improving overall network performance.

Route Poisoning

In computer networking, route poisoning is a technique used to prevent routing loops by marking a route as unreachable. When a router detects that a route has failed, it immediately sends an update to all its neighbors with the destination set to unreachable. This prevents any future packets from being forwarded towards the failed destination, thus avoiding loops. The marked route will remain poisoned for a predetermined amount of time before it is removed from the routing table.

The Difference Between Static and Dynamic IP Addressing

Static IP addressing is a type of network configuration where a device is given a fixed IP address that does not change over time. This means that every time the device connects to the network, it will be assigned the same IP address.

Dynamic IP addressing, on the other hand, is a type of network configuration where a device is given a temporary IP address that can change each time the device connects to the network. This is typically achieved through the use of a protocol called DHCP (Dynamic Host Configuration Protocol), which automatically assigns IP addresses to devices as they connect to the network.

The main advantage of using static IP addressing is that it provides a consistent, predictable network configuration, which can be helpful in certain situations, such as when running a server or other network services. However, it can also be more difficult to manage, as network administrators must manually assign IP addresses to each device on the network.

Dynamic IP addressing, on the other hand, is more flexible and easier to manage, as it allows IP addresses to be assigned automatically, without the need for manual configuration. However, it can also create some challenges, such as when trying to access devices on the network from a remote location, as the IP address may change each time the device connects to the network.

// Example of static IP configuration in Java

public class IPAddress {
   private static final String IP_ADDRESS = "192.168.1.100";
   
   public static void main(String[] args) {
      System.out.println("My IP address is: " + IP_ADDRESS);
   }
}

// Example of dynamic IP configuration using DHCP in Windows

1. Go to Control Panel > Network and Sharing Center.
2. Click on "Change Adapter Settings."
3. Right-click on your network connection and select "Properties."
4. Select "Internet Protocol Version 4 (TCP/IPv4)" and click "Properties."
5. Select "Obtain an IP address automatically" and "Obtain DNS server address automatically."
6. Click "OK" to save changes and close the window.

Understanding Network Congestion

Network congestion occurs when the volume of data being transmitted through a network exceeds its capacity to handle it effectively. This results in slow data transfer speeds or even complete blockages. Network congestion can happen due to various reasons such as heavy network traffic, inadequate network infrastructure, outdated hardware or software, and even cyber attacks. It can create negative impacts on network performance, user experience, and productivity. Therefore, it is important to implement proper network management strategies and tools to minimize the occurrence and severity of network congestion.

Types of Networks in CCNA

In CCNA, there are two types of networks - Local Area Networks (LANs) and Wide Area Networks (WANs). LANs are used for connecting devices within a small geographical area, such as an office building or campus. WANs, on the other hand, are used for connecting devices over a large geographical area, such as different cities or countries. Understanding the characteristics and differences between these two types of networks is essential in CCNA.

Types of Passwords for Cisco Routers

When setting up security measures for Cisco routers, there are several types of passwords that can be used:

• Console password: This password is used to restrict access to the router's console port.
• Auxiliary password: This password is used to restrict access to the router's auxiliary port.
• Enable password: This password is used to protect privileged EXEC mode, which allows users to make configuration changes to the router.
• Enable secret password: This password is a more secure version of the enable password, as it is stored using a non-reversible encryption.
• VTY password: This password is used to restrict access to the router via Telnet or SSH.

It is recommended to use strong, complex passwords that are difficult to guess. Additionally, it is important to regularly change these passwords as a security precaution.

Understanding Public IP and Private IP

Public IP is a globally unique IP address that is assigned to a device by the Internet Service Provider (ISP) and is accessible over the internet. It can be used to communicate with devices on the internet.

On the other hand, a private IP address is an IP address that is assigned to a device on a private network. It can only communicate with other devices on the same network. Private IP addresses are usually assigned by the network administrator.

The main difference between public and private IP addresses is that public IP address can be accessed over the internet, while private IP address is restricted to communication on the local network.

It's important to note that when accessing the internet from a device with a private IP address, the router used to connect to the internet assigns a public IP address to the device, so that it can communicate with other devices on the internet.

Main Function of the Application Layer in Networking

The main function of the application layer in networking is to provide a platform for applications to access network services. It establishes a communication interface between the network and the application, allowing them to exchange data and information. The application layer is responsible for identifying and establishing the availability of remote communication partners, synchronizing communication, and establishing privacy and security measures. In summary, the application layer provides high-level services to end-users, including email, file transfer, remote login, and other network-based services.

Explanation of OSPF Protocol

OSPF (Open Shortest Path First) is a routing protocol that is used to distribute data traffic in a network. It is a type of link-state protocol that enables routers to communicate with each other and exchange information about what networks they are connected to and their current state. This information is then used to build a routing table, which helps the routers determine the best path for data to take across the network. OSPF is commonly used in large enterprise networks due to its scalability, fast convergence times, and support for multiple paths.H3 tag: Differences between RIP and IGRP

RIP and IGRP are both routing protocols used in computer networks, but they differ in several ways.

1. Distance Vector vs. Hybrid Protocol: RIP is a distance vector protocol, while IGRP is a hybrid protocol that combines aspects of both distance vector and link-state protocols.

2. Metric Calculation: RIP uses hop count as its metric for path selection, while IGRP uses a composite metric that takes into account factors such as bandwidth, delay, reliability, and load.

3. Convergence Time: RIP has a slower convergence time than IGRP, which means that it takes longer for RIP to update its routing information in response to changes in the network topology.

4. Scalability: IGRP is more scalable than RIP, as it can support larger networks with more routers and subnets.

5. Password Authentication: IGRP supports password authentication for secure routing updates, while RIP does not provide this feature.

Overall, IGRP is a more advanced and feature-rich routing protocol when compared to RIP, but it also requires more configuration and management. It is important to understand the differences between these protocols when designing and implementing a network.

Code tag:

// No code provided since this is a theoretical question

Plain text in P tag. No links needed.