Read Questions / Answers for ACE your CCNA Interview
62 Important Questions/Answers for CCNA
1) Define the Routing?
The process of determining a path for data to travel from a source to a destination is called routing. Network layer devices known as routers are responsible for routing.
2) What is the job of Data Link Layer (DLL) ?
Verifying that messages are sent to the correct device is the responsibility of the Data Link layer. Framing is one of this layer's additional functions.
3) Advantages of using switches?
A switch assembles the bits from a signal it receives to form a frame. By using this procedure, it obtains access, reads the destination address, and then forwards the frame to the relevant port. Rather than sending the data over all ports, this is a very efficient way to send it.
4) Define the network congestion incident ?
Overuse of bandwidth by multiple users leads to network congestion. This is particularly valid for large networks that don't use network segmentation.
5) What do you mean by Window in networking terms?
The number of segments that can be sent from the source to the destination before receiving an acknowledgment is referred to as a window.
6) What bridge actually do in a network ?
In reality, a bridge serves to filter the vast network without causing the network's size to change.
7) Define the LAN switching method is used in CISCO Catalyst 5000.
The switch type used by Cisco Catalyst 5000 is store-and-forward switching. Before choosing whether or not to forward that data frame, it stores the entire frame to its buffers and runs a CRC check.
8) What is the LLC sublayer?
LLC stands for Logical Link Control sublayer. It can offer an application developer optional services. Using stop/start codes is one way to give the network layer flow control. Also, the LLC is able to offer error correction.
9) Distinguish the RIP & IGRP.
To find the optimal path to a network, RIP depends on the quantity of hops. However, IGRP considers numerous factors, including MTU, hop count, bandwidth, and reliability, before determining the optimal route to take.
10) Define the different memories used in a CISCO router?
1– NVRAM It stores the startup configuration file.
2– DRAM It stores the configuration file that is being executed.
3– Flash Memory – It stores the Cisco IOS.
11) What do you mean by BootP?
Diskless workstations connected to a network are booted using the BootP protocol. It stands for Boot Program in short. BootP is also used by diskless workstations to find both the IP address of the server PC and their own IP address.
12) Role of the Application Layer in networking?
In addition to supporting an application's communication components, the application layer offers network services to application processes that go beyond the parameters of the OSI reference model. Additionally, it synchronizes client and server applications.
13) User Mode VS Privileged Mode.
When using a CISCO router, User Mode is utilized for routine tasks like viewing system information, establishing connections with distant devices, and monitoring the router's status. Conversely, all of the User Mode's settings as well as additional ones are accessible in privileged mode. This is the mode that you can use to configure the router, including testing and debugging.
14) Do you know about 100BaseFX?
This Ethernet uses fiber optic cable as its primary means of transmission. The data speed is 100Mbps, denoted by the number 100.
15) What is full-duplex and half-duplex.
Full-duplex communication allows the transmitting and receiving devices to operate simultaneously, that is, to both transmit and receive at the same time. A device cannot receive while it is transmitting or vice versa in a half-duplex setup.
16) Define the term MTU?
The acronym MTU denotes Maximum Transmission Unit. It speaks of the largest packet size that can be transmitted across the data line without having to be fragmented.
17) Define the work of cut-through LAN switching.
When using Cut-Through LAN switching, the router reads the destination address before sending the data frame to the next network segment as soon as it is received.
18) Define the term 'latency' ?
A network device's latency is the difference in time between when it receives a data frame and when it sends it out again to another network segment.
19) In RIP, what is the limit comes to the number of hops?
There is a maximum of fifteen hop counts. If the number is greater than 15, the network is regarded as unreachable.
20) Define the term Frame Relay in the networking ?
A Wide Area Network (WAN) protocol called Frame Relay establishes and maintains virtual circuits to enable connection-oriented communication. It functions at both the Data Link and Physical Layers and has a high performance rating.
21) How is IPX routing configured on a Cisco router?
The first step is to use the “IPX routing” command to enable IPX routing. The IPX network then configures a network number and encapsulation method for each interface that is used on it.
22) Name the different IPX access lists?
Two types of IPX access lists :
1. Standard.
2. Extended.
Only the source or destination IP address can be filtered using a standard access list. When filtering a network, an Extended Access List makes use of the source and destination IP addresses, port, socket, and protocol.
23) Advantages of VLANs.
Groups can create collision domains using VLANs in addition to physical location. Networks can be established using VLANs according to various criteria, including function, hardware type, and protocol. Compared to traditional LANs, where collision domains are always connected to physical locations, this is a significant advantage.
24) Explain briefly about subnetting?
The process of splitting up a large parent network into smaller ones is called subnetting. Each subnet is given additional parameters or an identifier as a component of a network to represent its subnet number.
25) Briefly explain the advantages of a layered model in the networking industry?
There are numerous benefits to a layered network. Administrators can alter one layer without also altering the other layers thanks to this feature. By promoting specialization, the network industry can advance more quickly. Moreover, administrators can troubleshoot issues more quickly and effectively with a layered model.
26)Now UDP less favored as compared to TCP Why?
This is due to UDP's unsequenced and unreliability. Establishing virtual circuits and acknowledgments is beyond its capabilities.
27) Names the standards supported by the Presentation layer?
Numerous standards are supported by the presentation layer, ensuring accurate data presentation. For graphics, these include PICT, TIFF, and JPEG; for video and audio, they include MIDI, MPEG, and QuickTime.
28) How can we remotely configure a router?
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.
29) What can we see after type show protocol in CLI mode of router ?
1. Routed protocols that the router has set up.
2. The IP address that is linked to every interface.
3. The encapsulation technique set up on every interface.
30) In what way is an IP address represented?
There are three methods that could be used:
1. Firstly, in Dotted Decimal. Consider this: 192.168.0.1
2. In Binary Format 10000010.00111011.01110010.01110011
3. In hexadecimal we can write this: 82 1E 10 A1.
31) How can we enter in privileged mode? How can I return to user mode?
If you want to use privileged mode, type "enable" at the prompt. Enter the command "disable" to return to user mode.
32) Briefly explain about HDLC?
High-Level Data Link Control protocol is referred to as HDLC. It is a Cisco proprietary protocol. In CISCO routers, this encapsulation is used by default.
33) What is an internetwork and how can we create it ?
Internetworking is the practice of interconnecting multiple computer networks, such that any pair of hosts in the connected networks can exchange messages irrespective of their hardware-level networking technology. The resulting system of interconnected networks are called an internetwork,
When networks are connected via routers, internetworks are created. More specifically, for each network connected to the router, the network administrator allocates a logical address.
34) Define the term 'Bandwidth' ?
The maximum amount of data transmitted over an internet connection in a given amount of time.
The transmission capacity of a medium is referred to as its bandwidth. It measures the maximum volume that a transmission channel can support and is expressed in kilobases (Kbps).
35) What is hold down in networking ?
A hold down timer is a technique used by routers. When a router receives a notification about an offline route or node, the router will initiate a hold down timer allowing the offline router to recover and not update its routing table until the time expires.
In other words, a hold down keeps a router from receiving route updates until the network appears to be stable—until either an interface stops changing state (flapping) or a better route is learned.
A route enters into a hold down state when an update packet is received that indicates the route is unreachable.
36) What is the meaning of the term 'packets' in networking?
The end product of data encapsulation is a packet. These are data that have been covered by various OSI layer protocols. Another name for packets is datagrams.
37) What are segments in the OSI layer ?
A data stream that originates from the upper OSI layers and is prepared for transmission to the network is divided into segments. The Transport Layer's logic units are called segments.
38) Advantages of LAN switching.
1. Enables full duplex data transfer and reception
2. Modification of media rates
3. A simple and effective transfer
39) Explain Route Poisoning?
Route poisoning is a computer networking technique to prevent routing loops in dynamic routing protocols (such as the Routing Information Protocol or RIP) and maintain network stability.
It means removing a specific route from routers when that specific route is down or it's not reachable
In case of Rip: When a Route (ex 1.1.1.1/32 ) is down it removes that route from it's routing table and send a triggered update as network = 1.1.1.1 as metric 16. which makes this route as poison. when a router receives a route as metric 16 it just remove that route immediately.
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Line Diagram Showing Route poisoning Process |
40) How can we calculate the valid hosts in a subnet?
To solve this, the formula 256 - subnet mask is the most effective method. Any hosts found in between the subnets are regarded as legitimate.
41) Define the term 'DLCI' in networking.
Data Link Connection Identifiers, or DLCIs, are typically assigned by a frame relay service provider to each virtual circuit on the network in order to uniquely identify it.
When implementing a Frame-Relay topology, Data Link Connection Identifiers (DLCIs) are used as the Layer 2 addressing scheme. DLCIs are 10 bit values that identify virtual circuits (VCs).
These values must be locally unique (within the scope of the local device). Take a look at the following Frame-Relay topology:
The DLCI values on the hub must be unique for each VC that terminates on the Hub. The values of the DLCIs on the spokes can be different or can be the same, it makes no difference.
It is typically best practice to use the same DLCI numbers on either end of a VC. This makes it easier to manage a network, especially one with many spokes.
42) Give a brief explanation of the data encapsulation conversion processes.
Data from the end user is divided into segments from the perspective of a data transmitter. After being transferred to the subsequent layers, segments are transformed into packets or datagrams. After that, these packets are transformed into frames and sent to the network interface. Finally, before data is actually transmitted, frames are converted to bits.
43) Name different types of passwords used in securing a CISCO router?
There are actually five types of passwords that can be used. These enable secret, virtual terminal, console, and auxiliary.
44) Network segmentation a good idea when managing a large network, Why ?
Network segmentation facilitates network traffic and guarantees high bandwidth is always available to all users, which is beneficial for network administrators. Better performance results from this, particularly for expanding networks.
45) Distinguish between Physical and Logical Topology.
The signal path via the physical topology is referred to as the logical topology. The actual design of the network medium is known as the physical topology.
46) What causes a triggered update to reset the router hold-down timer?
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.
47) What is the difference between the switch, hub, and router?
48) Define the size of IP address?
Size of IP address is 32 bit for IPv4 and 128 bit for IPv6.
49) What is DHCP ?
DHCP stands for Dynamic Host Configuration Protocol. DHCP assigns an IP address automatically to host. You can also make static IPs for machines like printers, servers, routers, and scanners.
50) What BOOTP is?
BOOTP is a computer networking protocol used to deploy an IP address to network devices from a configuration server.
51) Explain why UDP is lease favored when compared to TCP?
It is because UDP is un-sequenced and unreliable. It is not capable of creating virtual circuits and acknowledgments.
52) State the difference between dynamic IP and static IP addressing?
Dynamically IP addresses are provided by DHCP server, and static IP addresses are given manually.
53) The ranges for the private IP?
Ranges for private IP are
Class A: 10.0.0.0 – 10.0.0.255
Class B: 172.16.0.0 – 172.31.0.0
Class C: 192.168.0.0 – 192.168.0.255
54) In how many ways you can access the router?
You can access it in three ways
Telnet (IP)
AUX (Telephone)
Console (Cable)
55) What is term EIGRP?
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.
56) What is the matric of EIGRP protocol?
EIGRP protocol consists of
Bandwidth
Load
Delay
Reliability
MTU
Maximum Transmission Unit
57) Mention what command you must use if you want to delete or remove the configuration data that is stored in the NVRAM?
Erase startup- config is the command you must use if you want to delete the configuration data that is stored in the NVRAM
58) Distinguish the TCP and UDP?
59) The difference between half-duplex and full-duplex?
Half-duplex communication allows for one direction of communication to happen at a time, whereas full-duplex communication allows for simultaneous communication in both directions.
60) What are the conversion steps of data encapsulation?
Conversion steps of data encapsulation includes
Layer one, two and Three ( Application/presentation/session) : Alphanumeric input from the user is converted into Data
Layer Four (Transport): Data is converted into small segments
Layer Five (Network): Data converted into packets or datagrams and Network header is added
Layer Six (Data Link): Datagrams or packets are built into frames
Layer Seven (Physical): Frames are converted into bits
61) What command do we give if router IOS is stuck?
Cntrl+Shift+F6 and X is the command we give if router IOS is stuck.
62) What route entry will be assigned to dead or invalid route in case of RIP?
In the case of RIP table entry, 16 hops will be assigned to dead or invalid route making it unreachable.
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