CCNA Interview Questions: Getting Started with Network Engineering Interviews

ccna interview questionsThe first step to being a certified Cisco engineer is the CCNA test. If you plan to be a network engineer, you first take the CCNA test and then you go for your interviews. The CCNA questions you’ll be asked at your interview are somewhat similar to those you’ll find on CCNA test. You spend a lot of money on these Cisco tests, but you’ll probably need to do some studying before your interview.

In addition to technical questions, be prepared for some questions regarding personality and your ability to work in a team environment. Most network engineers work with other engineers to support the entire system. Most jobs require you to work as a team, so be prepared for these types of questions as well. However, here are some CCNA questions you might encounter when you go for your technical interview as a network engineer.

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1) What is routing on a network?

This might seem like a basic question, but the interviewer might ask it just to see if you know the basics. Routing is done by routers. Routers have a routing table that send network traffic from one location to another location or segment on the network. Routers reduce network traffic compared to regular hubs. When a user sends network traffic across the network, a hub broadcasts to all segments of the network. With a router, the device analyzes the TCP/IP packet, sees the destination location, and then uses its lookup table to route the packet to the right network segment and destination. Switches also route traffic in a similar fashion.

2)  What is network congestion?

With all of the streaming applications and peer to peer software, network congestion is common on a large network. Network congestion occurs when too many people are trying to use limited bandwidth. Most companies have a limited amount of bandwidth they can use before they pay extra, which is why companies limit bandwidth by blocking streaming and peer to peer applications using firewalls.

3) What is the difference between RIP and IGRP?

When you send traffic on a network, the router (default gateway in Windows computer terminology) determines how to route the traffic. RIP determines where to send the traffic by determining the shortest amount of “hops.” A hop is the next router in the traffic’s path. Each router is considered a hop. With IGRP, several more factors are considered. IGRP takes into consideration the bandwidth availability, MTU, reliability and the amount of hops.

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4) What is the Application Layer in network connectivity?

The Application Layer is what your developers and software use to send traffic across the network. The Application Layer is especially important for synchronizing software between the server and the client machine.

5) What is the difference between user mode and privileged mode on a Cisco router?

These two modes are somewhat self-explanatory. The user mode allows the user to view router status and basic system information. With privileged mode access status, the router can be configured and all status messages and errors can be viewed. User mode and privileged mode separates standard users on the network and network administrators who need to not only view router status but also make changes to the router’s configurations.

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6) What is 100BaseFX?

As network technology improves, faster bandwidth speeds are offered. 10BaseFX used to be the speed standard for most networks, and you still find older networks with 10BaseFX. The “10” stands for 10 megabits per second or “10Mbps.” With 100BaseFX, the transmission speeds are 100 megabits per second or “100Mbps.”

7) What does MTU stand for?

MTU stands for “Maximum Transmission Unit.” When you configure a router, a default MTU is set. MTU determines the maximum size of a packet that is sent across the network. You can increase MTUs across the network, but this setting generally slows down the network compared to smaller MTU settings. Some network applications require larger MTU sizes, and that’s when you need to manually configure MTU sizes on your routers.

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8) What is the difference between full duplex and half duplex devices?

A full duplex device is preferable, because a full duplex device can send and receive data packets simultaneously. However, with a half duplex device, the device must finish receiving a message before it can then send a message. This can lead to slower transmission speeds and increase network latency.

9) What is network latency?

Network latency refers to the performance of one device when it communicates with another. Network latency is affected by bandwidth speeds, network card performance, cabling and congestion. High latency can also mean users won’t be able to properly communication with applications, which will “time out” if latency is too high.

10) What is subnetting on your network?

Subnetting is a way to segment your network into smaller “groups.” Subnetting is accomplished by manipulating the subnet mask, which is distributed to desktop computers and routers. Subnetting allows you to create smaller networks within your network, which then reduces congestion on larger networks.

11) Define bandwidth in terms of network architecture

While the term bandwidth is thrown around for most basic networking speeds and capacity, bandwidth is technically the data capacity of a network. It measures the volume of data for a transmission connection. Bandwidth is measured in kilobits per second or “Kbps.”

12) What are data packets?

Data packets are the encapsulation units that transmit information across a network. A data packet contains the sender’s information, the recipient’s information, and the data contained. It also contains the numeric identification number that defines the order and packet number. When you send data across the network, that information is segmented into data packets. The recipient then puts these packets together to be able to read the information. Basically, data packets contain the information and routing configurations for your transferred message.

13) Is it better to add a network segment to a growing network or continue to use the same subnet mask?

Growing networks start to suffer from network congestion. When you segment the network, routers are better able to route traffic to specific parts of the network without broadcasting signals across only one segment. When you reduce broadcasting, you lower congestion, which speeds up your network. With a growing large network, it’s better to start segmenting the network and create subnet masks for different segments.

14) What is DHCP?

Dynamic host configuration protocol (DHCP) automatically assigns an IP address to a given workstation client. DHCP is much better for managing IP addresses, because the DHCP server assigns and retires IP addresses as needed. It’s better organized than manually configuring IP addresses individually. When you manually assign IPs, you must keep track of each workstation and its IP. With DHCP, if a user logs off the network, the IP is released and given to the next user who needs it. You can also create static IPs for machines that need them, which includes printers, servers, routers and scanners. A DHCP server can be a server machine such as Windows or Linux or you can let your router set IP addresses.

These are a few questions that prepare you for basic CCNA interview tech interviews. While you aren’t expected to know all answers, it’s best to study and understand the basics before your interview.