In this post, we will be discussing the Top 50 Networking CCNA Interview Questions and Answers. It will be helpful for the candidates preparing for the interview or preparing for their CCNA exams. I have tried fairly to cover all the topics and for an in-depth overview, you can comment for any specific topic. We will be going from basic of networks to the advanced technologies. So let’s start without waiting.
” As they say, Get certified and work internationally anywhere on the globe”.IT certifications are playing an important role in the growth of engineers worldwide. Organizations like Cisco, Checkpoint, Microsoft, Oracle and others providing the international certifications to candidates to improve their individual skills and to make the knowledge-driven rich technical guys in the world. All the certifications are internationally recognized with the unique certification number.
Cisco is one of the leading organization which has a vast portfolio in network devices like Switches, Routers, Firewalls, WLC etc. It majorly covers about 60% of the total market of the world in routing, switching, data centre, wireless and security. Cisco provides the three level of certification to the engineers mainly known as CCNA-Cisco Certified Network Associate, CCNP-Cisco Certified Network Professional and last, is CCIE-Cisco Certified Internetwork Expert.
CCNA
1. CCNA—Cisco Certified Network Associate
CCNA is the entry-level certification. Most of the organization prefer the CCNA guy over the non-certified person.CCNA exam tests the ability of person like basic networking –which includes topic from switching like VLAN, STP, RSTP etc.Routing protocols like RIP,OSPF,EIGRP,BGP etc.Although CCNA helps in getting entry level jobs to the individual in addition to that it also builds up the expertise of the individual in basic networking terminologies.
CCNA
Exam Code:200-125
Duration:90 minutes
Question Types: Multiple Choice Question, Drag and Drop,Simulation
No. of Questions: 55-65
It is a piece of good news for all the freshers who are thinking to build up their career in the networking and security domain.CCNA should be on the checklist of goals to start a new and fresh career in IT field. All the major organizations demand over the CCNA engineers and CCNA have the huge potential to grab the entry level jobs in the market.
CCNA Syllabus:
- Basic Networking
- Basic Protocols–DHCP, ARP, PING etc.
- TCP/IP Layer,
- OSI Layer
- Cable and Connectors
- Access Control Lists
- VLAN, VTP,
- STP and RSTP
- Cisco IOS
- Routing– Default Routing,Static Routing,OSPF,EIGRP,RIP,BGP
- MPLS
- SYSLOG
- Cisco Password Recovery
- FTP
Top 50 Networking CCNA Interview Questions and Answers
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What is Networking?
Group of two or more computers connected together over the medium (cables or wireless) to share the information or resources like Printers, Scanners, File Servers etc. is known as Networking.
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What is LAN?
LAN stands for Local Area Network. It is a group of computers and network devices connected together within the same building or same office via switches or routers. The purpose of LAN is for communication within the organization.
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What is WAN?
WAN is a Wide Area Network. When we connect a group of two or more LAN’s together to share information and resources.WAN basically connects several LAN’s together which can be limited to the organization or accessible over the Public network. This technology provides high speed and relatively expensive as compared to the LAN.
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What are the protocols of WAN?
a.Point-to-Point Protocol (PPP)
b.Serial Line Internet Protocol (SLIP)
c.High-level Data Link Control Protocol (HDLC)- The default protocol. -
What is OSI reference Layer reference model? Name all the layers of the OSI Layers.
OSI is the Open System Interconnection model. It is the reference model which describes how the protocols work in the networking framework. There are 7 layers in the OSI model. Each layer has its defined function and every layer provides the services to their upper layers.
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List all the OSI layers?
a.Layer 7–Application Layer
b. Layer 6– Presentation Layer
c. Layer 5– Session Layer
d. Layer 4– Transport Layer
e. Layer 3– Network Layer
f. Layer 2 — Data Link Layer
g. Layer 1– Physical Layer
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How Transport Layer works. What is the major function of the Transport Layer?
Transport layer takes services from the network layer and provides its services toP
b. IPv6: IP version 6. It has a 128-bit address. -
What is Loopback address?
Loopback addresses are generally used for local testing purposes. We loop our local systems in order to test the TCP/IP stack are installed properly or not. We use 127.0.0.1 for loopback testing.
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Difference between Hubs, Switches and Routers?
a. Hub: Hub is kind of repeaters, which repeat the electronic signals out of its all ports except the one from which it receives the signals. It is a multi-port repeater. But with the increase of connecting device, the performance of the hub goes down because it has Single Collision Domain and Single Broadcast Domain. Hubs are outdated now and very randomly found in the organizations.
b. Switches: Switches are more intelligent devices than hub as they have multiple collision domains. The standard switches come with 24 ports or 48 ports. Switches are used to connect the end-user machines like Laptops, Desktops, Printers, IP Phones etc. One more advantage of using a switch is we can divide the LAN segments logically by using the concept of VLAN in managed switches. Switches are basically used for the communication between the LAN.
c. Routers: Routers are used to connect two or more LAN or WAN networks. They have excellent throughput and memory. Routers are intelligent devices which are used to store the Route in the routing table(memory). The main function of the router is to build the routing table and choose the best path (route) for the destination networks. Routers have multiple collision and multiple broadcast domain.
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What is a DMZ network and why it is required?
DMZ is the Demilitarized Zone that can be physical or logical sub-network which contains the servers like Active Directory, Web-server, File Server, DNS etc. and are directly exposed to the outside world/Untrust network.
We need DMZ because:
a. If someone attacks on my Trust network/LAN network & my trust zone get compromised, all of my production will come down but if I have separate the DMZ and Trust zone than the servers placed in the trusted zone will not be affected by the attack. My servers will be up and fully functional and be able to provide the services to the outside world for which they are meant for.b. The second Scenario is just reverse— If my DMZ zone gets compromised. So all the traffic coming to my DMZ zone will not access my Trust zone where all my developers & source code reside.
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What is a Firewall and Functions of Firewall?
Firewalls are security devices. They stop the attack in the organization. The firewall has two main functions:
a. To prevent unauthorized access within the network.
b. A firewall does the logical segmentation of the network.
Note: For more information about firewalls check my blog on What is Network Firewall?How Firewall works? -
What is ACL-Access Control List?
Access Control Lists (ACL’s) are the set of rules which are configured on the network devices like switches, routers and firewalls to permit or deny any traffic.
ACL’s filters the traffic on the basis of Source IP, Destination IP, Protocol/Services and Action( Permit or Deny) -
What are the types of ACL’s?
In CISCO we have —Standard ACL’s and Extended ACL’s
Further classification of ACL’s are:a. Named ACL
b. Time Base ACL
c. Ether type ACL
d. Web-based ACL -
How to display ACL’s on Cisco devices?
show access-list
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What is Data Encapsulation?
When data is transfer from the higher layer to the lower layer. Each layer adds its header to the original packet. This is known as Data Encapsulation.
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What is NIC?
NIC is a Network Interface Card which is a peripheral hardware device mounted on the desktop, laptops, printers etc. NIC helps in connecting to the network.It has unique mac-address that helps in the identification of the device over the network.
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Difference between Data Encapsulation and Data de-encapsulation?
When data is transfer from the higher layer to the lower layer. Each layer adds its header to the original packet. This is known as Data Encapsulation.
When data is transferred from the lower layer to the higher layer, each layer removes the information added by the other layers. It will remove the headers added by other layers and will insert its own header. This is known as Data de-encapsulation. -
What is DHCP and What is DORA process in DHCP?
DHCP is the Dynamic Host Control Protocol. It is the service used by hosts and network devices to get the addressing information dynamically.it works on the UDP port 67 and 68. It is a client-server architecture.DHCP server act as a centralized location for the clients from where they can request the IP address information from the server.DHCP is based on the Bootstrap Protocol(bootp).
It works on DORA process:
D stands for Discover
O stands for Offer
R stands for Request
A stands for Acknowledgement -
What is CDP and What is the purpose of CDP?
CDP stands for Cisco Discovery Protocol. It is independent of media and network protocol.
Purpose:
This protocol is used to manage the Cisco devices. Like gathering the information about the Cisco devices, how they are configured etc.
Pre-requisites for CDP:
Interfaces should be configured to support the SNAP(Subnetwork Access Protocol) headers.
Limitations of CDP:
a.CDP only works on Cisco devices.
b. It is supported on the Frame Relay multipoint subinterfaces.
c. If a neighbour device is not configured with IP address on the interface than the IP address of the next interface will be updated for the non configured interface. -
What is the Subnet mask?
Subnet Mask is a 32-bit number that masks the IP address. Subnet mask divides the IP address into two parts i.e Network Portion and Host Portion. The zero’s (0’s) represent the Host portion and ones(1) the network portion.
Ex: 255.255.255.0, 255.255.0.0, 255.0.0.0 -
What is Private and Public IP addresses?
Public IP Address: Public IP address are globally unique around the world. They are provided to the organizations to provide internet access and routable over the internet.
Private IP Address: Private IP address are used within the organizations for the communication within the networks. They are not unique over the globe and no routes are defined for them over the internet. -
What is APIPA?
APIPA is Automatic Private IP Addressing. When the machine is unable to get the IP information from the DHCP server and static IP is not configured in the system than the client machine will automatically assign an IP address to itself of APIPA range. The range used for APIPA addressing is 169.254.0.1 to 169.255.255.254 (class B).
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What is multi-casting?
Multicasting refers to one too many communication. For example, if we have 100 machines in our network and we want to communicate with only 30 machines than that type of communication will be referred to as Multicast Communication.
For Multicast communication we use class D IP addresses i.e224.x.x.x to 239.x.x.x and the MAC address range starts from 0100:5EXX: XXXX series where 0100:5E is the Organizationally Unique Identifier Address. -
What is Broadcasting and Define the address range for broadcasting?
Broadcasting refers to one to all communication. For example, if we have 50 machines in a network and we want to send one file from one computer to all other 49 machines, then we will use Broadcast communication. For Broadcast Communication we use the following address:
a. Broadcast IP address: 255.255.255.255 or 255.255.255.255/32
b. Broadcast MAC address: ffff:ffff:ffff or ff:ff:ff:ff:ff:ff -
What is the MAC address?
MAC stands for Media Access Controller address. It is a unique identifier assigned to the NIC(Network Interface Card) embedded into the devices. It is used for the communication at the data link layer of the network segments.
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What is the registry key and what is the purpose of registry key in Routers?
Registry Key is the hierarchical low-level database that stores the settings of the Operating system and its applications.
For recovering password we set up the registry key.a. In normal mode we use registry key 0x2102 to 0x210f.
b. While recovering the password we use 0x2142. -
Explain the different types of Firewall?
a.Packet Filter Firewall: Packet Filter Firewall are the 1st Generation of firewalls. Which filters the packet on the basis of Source IP address, Destination IP address, Services or Protocol and Action.
b.Stateful Firewall: Stateful firewall is a network firewall which monitors & maintains the connection table/state table for the traffic initiated from Trust zone to Untrust Zone & vice-versa.
c.Application Layer Gateway: It acts as an intermediate system between the Trust zone and the Untrust zone. All the request from the Trust zone comes to the Application Layer Gateway. The Application Layer gateway scans the request and decides according to rules whether to allow access or not.
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What is the difference between Static Route and Default Route?
Static Routing: For static routing, network administrator has to do manual configuration in the routers. The administrator manually adds the route in the routing table of the router. It is feasible for the small networks but cannot scale up the large networks.
Default Route: When we have only one entry and exit path for the packets in the organization to go over the internet than we used the Default routing. All the routers send the packets towards the single destination router.
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What is Administrative Distance? What is the Administrative Distance of Static Route, OSPF, EIGRP, BGP and RIP?
Administrative Distance is the trustworthiness or reliability of the information reflected by the Routing protocols. Less the Administrative Distance value more it’s reliable than others.AD values range from 0 to 255.
Static and Directly Connected Routes: 0
OSPF: 110
EIGRP: 90
BGP we have two values i.e. iBGP we have 200 and for eBGP, we have 20
RIP: 120 -
What is Switching?
Switching is the process of exchanging the information between different computer networks and segments by using Hardware address/MAC address of the devices. We use Switches for switching. Switches breakup the large collision domain into smaller collision domain.
The main function of switches are:
a. Receiving the data frames.
b. Processing the data frames.
c. Forwarding the data frames.
Types of Switching:
a. Circuit: In Circuit Switching a dedicated channel (circuit) is set up before the communication between the senders and receiver. Example of Circuit Switching is a telephone call.
b. Packet: In Packet switching the data is first fragmented into blocks or chunks known as Packets before the transformation. The packets are transferred independently based on the destination address and it is also not necessary it will take the same path for all the packets during transformation. -
What is VLAN and What is the purpose of VLAN?
VLAN stands for virtual LAN. It helps in logical segmentation of the LAN networks. It divides the large broadcast domain into small segments which help in reducing the congestion and broadcast storms over the networks.
Purpose of VLAN: VLAN does the grouping of devices on one or more LAN to communicate with each other regardless of there physical location because they are based on the logical grouping. -
What is the default ranges of VLAN?
VLAN Range Purpose
1 Normal Default on Cisco Switches.
2 – 1001 Normal For ethernet VLAN’s
1002 -1005 Normal For FDDI and token rings.
1006 -4094 Extended For ethernet VLAN’s -
What is a native VLAN?
Native VLAN is the untagged VLAN on 802.1q trunked switch port which is use for the communication between the network devices and to forward the untagged frames.
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What is the difference between Access Switch Port and Trunk Switch Port?
Access Port: Access Ports are the switch ports which are layer 2 devices and carry the traffic. Access ports carry the traffic of a single VLAN. It can’t carry the traffic of the multiple VLANs.
Example of Command Syntax for configuring Access port:
Router(config)interface fa0/10
(config)switchport access vlan 10
(config)exitTrunk Ports: Switch interface carrying the data of multiple VLANs is called Trunk Port. The purpose of trunk port is to interconnect the switches of different VLANs.
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What is VTP and What is the purpose of VTP?
VTP stands for VLAN Trunking Protocol, it is the mechanism to propagate the VLAN information throughout the switching environment. It basically uses Client-Server architecture.
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Which protocol is use in Cisco switches for avoiding the loops?
For loop avoidance, we use STP– Spanning Tree Protocol. It is the by default feature in the Cisco switches.
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What is STP and what is the purpose of using STP?
STP (Spanning Tree Protocol) provides the loop avoidance in the Cisco switches and by default enabled in the Cisco switches. The switch port goes in 4 states before forwarding the frames i.e. Blocking, Listening, Learning and Forwarding.
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What is a BPDU guard?
BPDU guard protects the integrity of the switch port that has enabled the port fast feature upon interfaces. By default, BPDU guard is not enabled on the Cisco switches.BPDU guard puts the port in a shutdown state when an error occurred.
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Define the timers of the STP states?
Blocking: 20 seconds or indefinite
Listening: 15 seconds
Learning: 15 seconds
Forwarding: no specific time -
What is RSTP?
It is the advanced version of the STP protocol.RSTP stands for Rapid Spanning Tree Protocol. It converges faster than the STP. RSTP has two more port states Alternate Port and Backup Port.
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What is an alternate port in RSTP?
By default, it is in discarding state but if current root port fails then alternate ports take over.
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What is Ether Channel?
It is a link aggregation protocol which allows grouping of the several ethernet physical link to create one logical link. The main advantage of Ether channel it provides redundancy and increases the link speed.
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What are the protocols of the Ether channel?
Ether channel has two protocols:
a. PAgP: Port Aggregation Protocol. It can be use only on cisco devices.
b. LACP: Link Aggregation Control Protocol. It can be use on both devices Cisco and non-Cisco. -
What are the modes of LACP and PAgP?
LACP Modes:
a. Passive Mode
b. Active Mode
PAgP Modes:
a. Auto
b. Desirable -
What is Routing?
Routing is the process of finding and choosing the best path from available paths for transferring the data from source to the destination network. For Routing, we use network devices called Routers.
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Explain the difference between class full and classless routing protocol?
Classful Routing Protocols: They do not carry the subnet mask information along with there routing updates. Thus FLSM (Fixed Length Subnet Masks) is only allowed in Classful Routing. Examples: RIPv1 and IGRP.
Classless Routing Protocols: They carry subnet mask information along with there routing updates. Thus VLSM is only allowed in the classless routing protocol. Examples of Classless Routing Protocols are RIPv2, EIGRP, OSPF, and IS-IS.
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Explain the OSPF Routing protocol?
OSPF stands for Open Shortest Path First. It is an open standard routing protocol and comes under the category of Classless Routing Protocol. Administrative distance is 110 and represented by O in routing table.
It works upon the Dijkstra Algorithm.a. First, the shortest path is set up between the source and the destination. All the OSPF routers build up there topology.
b.In the next phase, all the OSPF routers exchange their databases. -
What is Backbone area in the OSPF?
The Backbone area is the core of the OSPF network. All the other Area’s connects to it and all the traffic between the areas flows from this area. The routing updates and neighbour information of the other area’s is transverse through Backbone Area.
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What is the election process of Designated Router in the OSPF process?
a. Highest Priority
b. Highest Router ID
c. Highest IP address. -
Explain the difference between TCP and UDP?
Comparison chart between TCP and UDP protocols
Difference between TCP and UDP
For more information about CIsco certification do visit Cisco official website Cisco Certifications
Conclusion
CCNA act as an entry gate into the world of networking and security. With good knowledge, hands-on lab practice and CCNA certification one can fairly gets the Associate level jobs in the organization.
Feel free to comment and share your views. I will be posting new articles over CCNA and basic networking. Keep Sharing and Learning!! -