Here are CCNA interview questions and answers for fresher as well experienced candidates to get their dream job.
Routing is the process of finding a path on which data can pass from source to destination. Routing is done by a device called routers, which are network layer devices.
The job of the Data Link layer is to check messages are sent to the right device. Another function of this layer is framing.
When a switch receives a signal, it creates a frame out of the bits that were from that signal. With this process, it gains access and reads the destination address, after which it forwards that frame to the appropriate port. This is a very efficient means of data transmission, instead of broadcasting it on all ports.
Network congestion occurs when too many users are trying to use the same bandwidth. This is especially true in big networks that do not resort to network segmentation.
A Window refers to the number of segments that are allowed to be sent from source to destination before an acknowledgment is sent back.
Not really. What a bridge actually does is to take the large network and filter it, without changing the size of the network.
CISCO Catalyst 5000 uses the Store-and-forward switching method. It stores the entire frame to its buffers and performs a CRC check before deciding whether or not to forward that data frame.
The LLC sublayer stands for Logical Link Control. It can provide optional services to an application developer. One option is to provide flow control to the Network layer by using stop/start codes. The LLC can also provide error correction.
RIP relies on the number of hops in order to determine the best route to a network. On the other hand, IGRP takes consideration many factors before it decides the best route to take, such as bandwidth, reliability, MTU and hop count.
Different memories used in a CISCO router are:
– NVRAM stores the startup configuration file.
– DRAM stores the configuration file that is being executed.
– Flash Memory – stores the Cisco IOS.
BootP is a protocol that is used to boot diskless workstations that are connected to the network. It is short for Boot Program. Diskless workstations also use BootP in order to determine its own IP address as well as the IP address of the server PC.
The Application Layer supports the communication components of an application and provides network services to application processes that span beyond the OSI reference model specifications. It also synchronizes applications on the server and client.
User Mode is used for regular task when using a CISCO router, such as to view system information, connecting to remote devices, and checking the status of the router. On the other hand, privileged mode includes all options that are available for User Mode, plus more. You can use this mode in order to make configurations on the router, including making tests and debugging.
This is Ethernet that makes use of fiber optic cable as the main transmission medium. The 100 stands for 100Mbps, which is the data speed.
In full-duplex, both the transmitting device and the receiving device can communicate simultaneously, that is, both can be transmitting and receiving at the same time. In the case of half-duplex, a device cannot receive while it is transmitting, and vice versa.
MTU stands for Maximum Transmission Unit. It refers to the maximum packet size that can be sent out onto the data line without the need to fragment it.
In Cut-Through LAN switching, as soon as the router receives the data frame, it will immediately send it out again and forward it to the next network segment after reading the destination address.
Latency is the amount of time delay that measures the point from which a network device receives a data frame to the time it sends it out again towards another network segment.
The maximum limit is 15 hop counts. Anything higher than 15 indicates that the network is considered unreachable.
Frame Relay is a WAN protocol that provides connection-oriented communication by creating and maintaining virtual circuits. It has a high-performance rating and operates at the Data Link and Physical Layers.
The initial thing to do is to enable IPX routing by using the “IPX routing” command. Each interface that is used in the IPX network is then configured with a network number and encapsulation method.
There are two types of IPX access lists
Standard Access List can only filter the source or destination IP address. An Extended Access List uses the source and destination IP addresses, port, socket, and protocol when filtering a network.
VLANs allow the creation of collision domains by groups other than just physical location. Using VLANs, it is possible to establish networks by different means, such as by function, type of hardware, protocol, among others. This is a big advantage when compared to conventional LANs wherein collision domains are always tied to physical location.
Subnetting is the process of creating smaller networks from a big parent network. As a part of a network, each subnet is assigned some additional parameters or identifier to indicate its subnet number.
A layered network offers many advantages. It allows administrators to make changes in one layer without the need to make changes in the other layers. Specialization is encouraged, allowing the network industry to make progress faster. A layered model also lets administrators troubleshoot problems more efficiently.
It’s because UDP is unreliable and unsequenced. It is not capable of establishing virtual circuits and acknowledgments.
Presentation layer supports many standards, which ensures that data is presented correctly. These include PICT, TIFF, and JPEG for graphics, MIDI, MPEG and QuickTime for Video/Audio.
In cases when you need to configure a router remotely, the most convenient is to use the Cisco AutoInstall Procedure. However, the router must be connected to the WAN or LAN through one of the interfaces.
– routed protocols that is configured on the router.
– the address assigned on each interface.
– the encapsulation method that was configured on each interface.
It can be done in three possible ways:
– using Dotted-decimal. For example: 192.168.0.1
– using Binary. For example: 10000010.00111011.01110010.01110011
– using Hexadecimal. For example: 82 1E 10 A1
To access privileged mode, you enter the command “enable” on the prompt. In order to get back to user mode, enter the command “disable.”
HDLC stands for High-Level Data Link Control protocol. It is a propriety protocol of CISCO. It is the default encapsulation operated within CISCO routers.
Internetworks are created when networks are connected using routers. Specifically, the network administrator assigns a logical address to every network that connects to the router.
Bandwidth refers to the transmission capacity of a medium. It is a measure of how much volume a transmission channel can handle, and it is measured in Kbps.
Hold-downs prevent regular update messages from reinstating a downed link by removing that link from update messages. It uses triggered updates to reset the hold-down timer.
Packets are the results of data encapsulation. These are data that have been wrapped under the different protocols of the OSI layers. Packets are also referred to as datagrams.
Segments are sections of a data stream that comes from the upper OSI layers and ready for transmission towards the network. Segments are the logic units at the Transport Layer.
– allows full duplex data transmission and reception
– media rate adaption
– easy and efficient migration
Route Poisoning is the process of inserting a table entry of 16 to a route, making it unreachable. This technique is used in order to prevent problems caused by inconsistent updates on a route.
The best way to go about this is to use the equation 256 minus the subnet mask. The hosts that are considered valid are those that can be found between the subnets.
DLCI, or Data Link Connection Identifiers, are normally assigned by a frame relay service provider in order to uniquely identify each virtual circuit that exists on the network.
From a data transmitter’s point of reference, data from the end user is converted to segments. Segments are then passed on to the other layers and converted into packets or datagrams. These packets are then converted into frames before passing on to the network interface. Finally, frames are converted to bits prior to actual data transmission.
There are actually five types of passwords that can be used. These enable secret, virtual terminal, console, and auxiliary.
For a network administration, segmenting a network would help ease network traffic and ensures that high bandwidth is made available at all times for all users. This translates to better performance, especially for a growing network.
The hostname and the Interfaces. The hostname is the name of your router. The Interfaces are fixed configurations that refer to the router ports.
Logical Topology refers to the signal path through the physical topology. Physical Topology is the actual layout of the network medium.
This may happen when the hold-down timer has already expired, or when the router received a processing task that incidentally was proportional to the number of links in the internetwork.
A. erase running-config
B. erase startup-config
Correct Answer: B. erase startup-config
Hostname: Branch Hostname: Remote
PH# 123-6000, 123-6001 PH# 123-8000, 123-8001
SPID1: 32055512360001 SPID1: 32055512380001
SPID2: 32055512360002 SPID2: 32055512380002
ISDN switch-type basic ni
username Remote password cisco
IP address 10.1.1.1 255.255.255.0
PPP authentication chap
ISDN spid1 41055512360001
ISDN spid2 41055512360002
dialer map IP 10.1.1.2 name Remote 1238001
dialer-list 1 protocol IP permit
Correct Answer: (config-if)# dialer-group 1
Correct Answer: A. The highest IP address of any physical interface.
| Hub | Switch | Router |
|---|---|---|
| Hub has a single broadcast domain and collision domain. Anything comes in one port is sent out to the others. | It is a device that filters and forwards packets between LAN segments. Switches have a single broadcast domain and multiple collision domains. It supports any packet protocol, as such it operates at the data link layer 2 and layer 3 | Router is a device which transmits data packets along networks. |
Size of IP address is 32 bit for IPv4 and 128 bit for IPv6.
A data packet consists of sender’s information, recipient’s information, and the data contained. It also has the numeric identification number that defines the packet number and order. When data is sent across the network, that information is segmented into data packets. In short, data packets carry the information and routing configuration for your transferred message.
DHCP stands for Dynamic Host Configuration Protocol. DHCP assigns an IP address automatically to a given workstation client. You can also make static IPS for machines like printers, servers, routers, and scanners.
BOOTP is a computer networking protocol used to deploy an IP address to network devices from a configuration server.
It is because UDP is un-sequenced and unreliable. It is not capable of creating virtual circuits and acknowledgments.
Dynamically IP addresses are provided by DHCP server, and static IP addresses are given manually.
Ranges for private IP are
You can access it in three ways
EIGRP stands for Enhanced Interior Gateway Routing Protocol it is a routing protocol designed by Cisco Systems. It is availed on a router to share routes with other routers within the same autonomous system. Unlike other routers like RIP, EIGRP only sends incremental updates, decreasing the workload on the router and the amount of data that needs to be transferred.
EIGRP protocol consists of
Clockrate enables the routers or DCE equipment to communicate appropriately.
Erase startup- coding is the command you must use if you want to delete the configuration data that is stored in the NVRAM
TCP and UDP both are protocols for sending files across computer networks.
| TCP (Transmission Control Protocol) | UDP (User Datagram Protocol) |
|---|---|
| TCP is connection oriented protocol. When connection lost during transferring files, the server would request the lost part. While transferring a message, there is no corruption while transferring a message | UDP is based on connectionless protocol. When you send data, there is no guarantee whether your transferred message will reach there without any leakage |
| The message will deliver in the order it is sent | The message you sent may not be in the same order |
| Data in TCP is read as a stream, where one packet ends, and another begins | Packets are transmitted individually and are guaranteed to be whole if they arrive |
| Example of TCP includes World Wide Web, file transfer protocol, e-mail, | Example for UDP are VOIP (Voice Over Internet Protocol) TFTP ( Trivial File Transfer Protocol), |
Full duplex means that the communication can occur in both directions at the same time, while half-duplex means that the communication can happen in one direction at a time.
Conversion steps of data encapsulation includes
Cntrl+Shift+F6 and X is the command we give if router IOS is stuck.
Route poisoning is a technique of preventing a network from transmitting packets through a route that has become invalid.
In the case of RIP table entry, 16 hops will be assigned to dead or invalid route making it unreachable.
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