CCNA Interview Questions
CCNA is the first step one takes to enter the networking field. It validates your knowledge to configure, install, operate and troubleshoot networking devices. CCNA helps many potential network engineers to get the desired jobs, but passing an interview won't be easy without proper preparation. So, here are some of the most asked CCNA interview questions and answers.
These CCNA interview questions are curated very carefully with the help of some of the leading researchers in the networking field to help you clear any CCNA interview. These CCNA interview questions are beneficial for both experienced and fresher candidates.
CCNA Interview Questions and Answers
This blog has listed the top 10 CCNA Interview questions and answers that are most commonly asked in any CCNA interview. These questions are carefully hand-picked, so you will definitely come across one or more questions in any CCNA interview.
If you want the complete list of CCNA Interview questions, you can get the CCNA Interview questions and answers PDF at the end of this blog.
Q1 – What is a Router?
Answer – A router is a device that enables communication between two or more different logical networks. It is a network layer-3 device that is used to forward data packets in a network.
A router examines the destination IP Address of the data packet and uses the header and routing table to find the best route for transmission.
Q2 – What are the different modes in a router?
Answer – There are basically 3 different modes in a router which are:
- User Mode:
The user-mode only allows us to do basic monitoring. Only limited show commands work in this mode and it is denoted by the ">" sign.
For ex: Enable, ping, traceroute, etc. Router>
- Privilege Mode:
Only monitoring, verification, and troubleshooting commands work in this mode. It is denoted by “#”.
For ex: show, configure terminal, write, etc. Router#
- Global Configuration Mode:
This mode affects the operations of the device. It is generally used to view all the configurations of the device and it is often used to perform high-level tasks on devices. It is denoted by “(config)#”.
For ex: Hostname, etc. Router(config)#
Q3 – What is the OSI Reference Model and what are its different layers?
Answer – OSI stands for Open System Interconnect. The OSI Reference model explains how information and data communication occurs over a network, and it was developed by International Organization for standardization (ISO) in 1984.
It consists of 7 Layers which are:
- Application Layer:
It's responsible for providing an interface for users to interact with application services or network services.
- Presentation Layer:
It's responsible for defining a standard format for the data. Encoding and Decoding is the major function that takes place at this layer.
- Session Layer:
This layer is responsible for establishing, maintaining, and terminating the sessions. The Session ID is used to identify a session or interaction.
- Transport Layer:
It provides a data delivery mechanism between applications in the network. The Transport layer is the major function layer in the OSI model. It performs:
- Identifying service
- Multiplexing & De-multiplexing Segmentation
- Error correction
- flow control
- Transport layer protocols
The protocols which take care of data transport at the transport layer are TCP/UDP.
- Network Layer:
It provides logical addressing path determination (routing). The protocols that work in this layer are: -Routed Protocol, Routing Protocol.
- Data Link Layer:
It provides communication with the network layer. Mac (media access control) it provides reliable data transit across a physical link.
- Physical Layer:
It defines the electrical and mechanical functional specification for communication between the network devices.
Q4 – What is the difference between a Half-duplex and a Full-duplex?
Answer – In the half-duplex, data flows only in one direction at a given time. Data can flow in both directions but only one at a time.
For Example - Walkie-Talkie or Hub
In the Full-duplex, data transmission can happen in both the directions simultaneously.
For example: Telephone or Switch
Q5 – What is the difference between Unicast, Multicast and Broadcast?
Answer – Cast stands for transmission of data packets from sender to recipient in all these terms.
It is a one-to-one communication technique where communication takes place between a single client and a single recipient in a network.
For Example: Browsing any website
Multicast is a group type of communication where one or more senders transfer data to receivers. It uses the IGMP (Internet Group Management Protocol) to determine the receiver group.
For Example: Sending an Email to a particular group
Broadcast is a one-to-many type of communication where data communication occurs between all the devices in the network. In broadcast, data is sent by one sender once and a copy of that data is available to all the devices in that network.
For Example: Television
To better understand all the types of communications, you can also watch this video:
Q6 – What is the difference between a hub, switch and router?
Answer – A hub is a Physical Layer (Layer 1) device, whereas a Switch is a Data link layer (Layer 2) device, and a router is a Network layer (Layer 3) device.
A hub is a very simple device that transmits the data from input to all the outputs. A switch is an intelligent device that carefully inspects the message address and delivers it to that particular device. A router is a very sophisticated and intelligent which reads IP addresses and directs the packets to another network with a specified IP address.
Routers also build address tables that help in routing, and that is why it is a more expensive device than switch and hub.
Another difference is how these devices work:
A hub works on the basis of broadcasting, while Switch works based on MAC address and the router works on IP address.
Q7 – What are Broadcast Domain and Collision Domain?
Answer - Broadcast Domain - Broadcast is a type of communication where the sending device sends a single copy of data. That copy of data gets delivered to every other device in the network segment.
Collision Domain - It is a network scenario where one device sends a packet on a network segment forcing every other device on that same segment to pay attention to it. At the same time, if a different device in that same segment to pay attention to it.
Q8 – What is TCP/IP Model?
Answer – TCP/IP stands for Transmission Control Protocol/Internet Protocol. The Department of Defense developed the TCP/IP model in the 1960s based on standard protocols.
It is known as the concise version of the OSI model and it contains 4 layers instead of 7 (like in OSI model). These 4 layers are:
The prime purpose of the TCP/IP model is to allow communication over large distances. It also helps us understand how a computer should be connected to the internet and how it should communicate.
Q9 – What is ARP?
Answer – ARP stands for Address Resolution Protocol. It is a network protocol used to map a network layer protocol address (IP address) to a data link layer hardware address (MAC address). ARP resolves the IP address to the corresponding MAC address.
Q10 – What is the MAC Format?
Answer - It is a 12 Digits 48 Bit(6byte) Hardware address written in Hexadecimal format. It consists of two parts: -
• IEEE assigns the first 24 Bits of OUI (Organizationally Unique Identifier).
• The last 24 Bits are Manufacturing-assigned Code.
CCNA interview Questions and Answers PDF
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Frequently Asked Questions:
Question – What are the basics of CCNA?
Answer – Some of the basics that are covered in the CCNA certification course are:
- Networking Fundamentals
- OSI and TCP/IP Models
- Routers and Switches
- Routing Protocols
- IP Addressing
- IP Services
- WLAN and VLAN
- Programmability, etc.
These are the basics of CCNA that you get to learn in the paid CCNA course from PyNet Labs. Check out PyNet Labs’ official CCNA page for more information.
Question – Is the CCNA exam hard?
Cisco certifications are considered one of the toughest exams in the world but on the bright side, these certifications prepare you for real job expectations. The CCNA certification is the first in Cisco’s long list of certificates, and it is comparatively easy to other Cisco certifications. However, it is not as easy as other certifications out there.
Question – Is CCNA a beginner?
Answer – Yes, CCNA is the beginning certification in the long-list of Cisco certifications. It introduces you to networking fundamentals and is one of the best certifications for beginners.
Question – Can I pass CCNA with self-study?
Answer – CCNA certification exam tests your knowledge of networking fundamentals and experience with networking devices which is attainable through self-study. There are many books, videos and study material available online for self-studying and passing this exam.