CCNA Interview Questions

VLANs are virtual LANs that can logically separate devices into different broadcast domains, regardless of their physical location. Some benefits of using VLANs are:

Improved security: VLANs can isolate sensitive or confidential data from unauthorized access.

Reduced congestion: VLANs can reduce the amount of broadcast traffic and collisions in a network.

Enhanced performance: VLANs can increase the bandwidth and throughput of a network by reducing the number of devices competing for the same resources.

Easier management: VLANs can simplify the administration and configuration of a network by grouping devices based on their function, department, or location.

Routing protocols are protocols that enable routers to exchange routing information and determine the best path to a destination network. There are two types of routing protocols:

Distance vector protocols: These protocols use the distance (hop count) and direction (next hop) to a destination network as the routing metric. They periodically broadcast their entire routing table to their neighbors. Examples of distance vector protocols are RIP and IGRP.

Link state protocols: These protocols use the cost (bandwidth, delay, reliability, etc.) of each link in the network as the routing metric. They maintain a database of the topology of the network and use a shortest path algorithm to calculate the best path to a destination network. They only send updates when there is a change in the network. Examples of link state protocols are OSPF and IS-IS.

Subnetting is the process of dividing a network into smaller subnetworks, each with its own network address and subnet mask. Subnetting is used for:

Efficient utilization of IP addresses: Subnetting can reduce the wastage of IP addresses by allocating them according to the size and requirement of each subnetwork.

Improved network performance: Subnetting can reduce the amount of broadcast traffic and congestion in a network by limiting the scope of broadcasts to each subnetwork.

Enhanced network security: Subnetting can isolate different subnetworks from each other and prevent unauthorized access or attacks.

NAT stands for Network Address Translation and it is a process that allows a device to translate private IP addresses to public IP addresses and vice versa. Some advantages and disadvantages of NAT are:

      Advantages:

NAT can conserve public IP addresses by allowing multiple devices to share a single public IP address.

NAT can provide a layer of security by hiding the internal network structure and IP addresses from the external network.

NAT can enable devices with different IP addressing schemes to communicate with each other.

      Disadvantages:

NAT can introduce latency and overhead in the packet processing.

NAT can break some applications that rely on end-to-end connectivity or use the IP address as an identifier.

NAT can complicate the troubleshooting and monitoring of network traffic.

TCP and UDP are transport layer protocols that provide different services for data transmission. The functions of TCP and UDP are:

TCP: TCP stands for Transmission Control Protocol and it provides a reliable, connection-oriented, and full-duplex service for data transmission. TCP establishes a connection between the source and destination devices before sending data and uses sequence numbers, acknowledgments, and timers to ensure that all data segments are delivered correctly and in order. TCP also provides flow control and congestion control mechanisms to regulate the rate of data transmission and avoid network congestion.

UDP: UDP stands for User Datagram Protocol and it provides an unreliable, connectionless, and best-effort service for data transmission. UDP does not establish a connection between the source and destination devices and does not guarantee the delivery, order, or integrity of data segments. UDP is faster and more efficient than TCP, but it does not provide any error recovery or congestion control mechanisms. UDP is suitable for applications that require low latency, high throughput, or real-time communication, such as voice or video streaming.

Static routing and dynamic routing are two methods of configuring routing information on routers. The differences between static and dynamic routing are:

Static routing: Static routing is the manual configuration of routing entries on routers. Static routing is simple and secure, but it is not scalable or adaptable to network changes. Static routing is suitable for small or stable networks that have a fixed topology and a low number of routers.

Dynamic routing: Dynamic routing is the automatic configuration of routing entries on routers using routing protocols. Dynamic routing is complex and less secure, but it is scalable and adaptable to network changes. Dynamic routing is suitable for large or dynamic networks that have a variable topology and a high number of routers.

TCP and IP are two protocols that work together to enable data communication over the internet. TCP and IP operate at different layers of the OSI model and have different functions. The differences between TCP and IP are:

TCP: TCP stands for Transmission Control Protocol and it operates at the transport layer of the OSI model. TCP provides a reliable, connection-oriented, and full-duplex service for data transmission. TCP establishes a connection between the source and destination devices before sending data and uses sequence numbers, acknowledgments, and timers to ensure that all data segments are delivered correctly and in order. TCP also provides flow control and congestion control mechanisms to regulate the rate of data transmission and avoid network congestion.

IP: IP stands for Internet Protocol and it operates at the network layer of the OSI model. IP provides an unreliable, connectionless, and best-effort service for data transmission. IP does not establish a connection between the source and destination devices and does not guarantee the delivery, order, or integrity of data segments. IP is responsible for routing data packets across the internet using logical addresses (IP addresses) and routing tables. IP also supports fragmentation and reassembly of data packets to accommodate different network media and MTU sizes.

LAN and WAN are two types of networks that differ in their size, scope, and characteristics. The differences between LAN and WAN are:

LAN: LAN stands for Local Area Network and it is a network that covers a small geographic area, such as a home, office, or building. LANs are usually owned and managed by a single entity, such as an individual, a company, or an organization. LANs typically use Ethernet or Wi-Fi as the network media and have high bandwidth, low latency, and low cost. LANs are suitable for sharing resources, such as files, printers, or internet access, among a limited number of devices.

WAN: WAN stands for Wide Area Network and it is a network that covers a large geographic area, such as a city, country, or continent. WANs are usually owned and managed by multiple entities, such as service providers, governments, or corporations. WANs typically use leased lines, satellite links, or cellular networks as the network media and have low bandwidth, high latency, and high cost. WANs are suitable for connecting remote or distributed devices, such as branch offices, data centers, or cloud services, over long distances.

DHCP and DNS are two protocols that provide different services for network devices. The differences between DHCP and DNS are:

DHCP: DHCP stands for Dynamic Host Configuration Protocol and it is a protocol that assigns IP addresses and other network parameters to devices dynamically. DHCP operates at the application layer of the OSI model and uses a client-server model. A DHCP client requests an IP address from a DHCP server, which responds with an IP address and other network parameters, such as subnet mask, default gateway, and DNS server. DHCP simplifies the network configuration and management by eliminating the need for manual IP address assignment and avoiding IP address conflicts.

DNS: DNS stands for Domain Name System and it is a protocol that resolves domain names to IP addresses and vice versa. DNS operates at the application layer of the OSI model and uses a distributed database model. A DNS client queries a DNS server, which responds with the IP address or the domain name of the requested resource. DNS facilitates the network communication and navigation by allowing users to use human-readable names, such as www.google.com, instead of numerical IP addresses, such as 172.217.160.78.

RIP depends on the number of hops so as to decide the best route to a network. Whereas IGRP takes thought numerous variables before selecting the best route to take, for example, transmission capacity, reliability, MTU and hop count.

Diverse memories utilized as a part of a CISCO router are:

•   NVRAM stores the startup setup record file
  
•    DRAM stores the setup record that is being executed
  
•    Flash Memory stores the Cisco IOS.
  

BootP is a convention that is utilized to boot diskless workstations that are associated with the system networks. It is short for Boot Program. Diskless workstations likewise utilize BootP keeping in mind the end destination to decide its own particular IP address, an additionally the IP address of the server PC.

The Application Layer underpins the corresponding segments of an application and offers network service to the application process that traverse beyond the OSI reference model specifications. It likewise synchronizes applications on the server and the client.

Client/user Mode is utilized for customary undertaking when utilizing a CISCO switch, for example, to see framework data, associating with remote gadgets, and checking the status of the switch. For privileged mode incorporates all alternatives that are accessible for User Mode. You can also utilize this mode so as to make configurations on the switch, including making tests and debugging.

In full-duplex, both the transmitting gadget and the receiving gadget can impart at the same time that is, both can be transmitting and accepting in the meantime. Whereas in the case of half-duplex, a gadget can't be able to receive while it is transmitting, and vice versa.

MTU implies for Maximum Transmission Unit. It alludes to the maximum packet size that can be conveyed onto the information line without the need to section it.

In Cut-Through LAN switching, when the router gets the data frame, it will quickly send it out again and forward it to the following network segment subsequent to perusing the destination address.

Latency is the measure of time defer that measures the point from which a network gadget receives an information frame to the time it sends it out again towards another network section.

The most extreme breaking point is 15 hop counts. Anything higher than 15 demonstrates that the system is viewed as inaccessible.

It is a WAN protocol which provides association arranged correspondence by making and keeping up virtual circuits. It has an elite rating and works at the Data Link and the Physical Layers.

The underlying activity is to empower IPX routing by utilizing the "IPX routing" command. Every interface that is utilized as a part of the IPX network is then designed with a network number and epitome strategy. 

There are two sorts of IPX access lists such as: 

Standard and Expanded

Standard Access List can just channel the source or the destination IP address. 

An Extended Access List utilizes the source and destination IP addresses, port, attachment, and protocol while filtering a network.

VLANs permit the creation of collision domains by bunches other than simply physical area. Utilizing VLANs, it is conceivable to build up networks by various means.

Subnetting is the method of creating small networks from a major parent network. As a piece of a network, each subnet is assigned some extra parameters or identifier to show its subnet number.

A layered system offers numerous points of interest. It enables the administrations to roll out improvements in a single layer without the need to roll out improvements in alternate layers. Specialization is empowered, enabling the network business to make progress at a faster speed. A layered model likewise gives overseers a chance to investigate issues all the more productively.

This is on account of UDP is problematic and unsequenced. It isn't fit for setting up virtual circuits and affirmations. 

Presentation layer underpins numerous measures, which guarantees that information is displayed accurately. These incorporate PICT, TIFF, and JPEG for designs, MIDI, MPEG and QuickTime for Video/Audio.

In situations when you have to arrange a router remotely, the most helpful is to utilize the Cisco Auto Install Procedure. Nonetheless, the router must be associated with the WAN or LAN through one of the interfaces. 

 Routed protocols that are configured on the router

* The address relegated on every interface

 * The exemplification strategy that was configured on every interface. 

It should be possible in three conceivable ways:

1. Utilizing the Dotted-decimal. For instance: 192.168.0.1
   
2. Utilizing the Binary. For instance: 10000010.00111011.01110010.01110011
   
3. Utilizing the Hexadecimal. For instance: 82 1E 10 A1
   

To get to privileged mode, you need to enter the command as enable on the prompt. While to change it back to the user mode, enter the command as disable.

HDLC implies for High-Level Data Link Control protocol. It is an appropriateness protocol of CISCO. It is the default embodiment worked inside CISCO switches/routers. 

Internetworks are made when networks are associated utilizing routers. In particular, the network manager doles out a logical address to each network that interfaces with the switch/router.

Bandwidth alludes to the transmission limit of a medium. It is a measure of how much volume a transmission channel can deal with, and it is estimated in Kbps.

Hold-downs keep standard update messages from re-establishing a downed link by expelling that connection from update messages. It utilizes activated updates to reset the hold-down timer.

Packets are formed from the data encapsulation. These are information that has been wrapped under the diverse protocols of the OSI layers. Packets are additionally alluded to as datagrams.

Segments are the sections of the data stream that originates from the upper OSI layers and prepared for transmission towards the network. Segments are the rationale units at the Transport Layer. 

  It permits full duplex information transmission and reception

* Media rate adaption

* Simple and productive movement. 

It is the procedure of embedding a table entry of 16 to a route, making it inaccessible. This method is utilized as a part of a request to prevent the issues caused by conflicting reports on a route.

The most ideal approach to this is to utilize the equation 256 minus the subnet mask. The hosts that are viewed as legitimate are those that can be found between the subnets.

DLCI implies for Data Link Connection Identifiers, are typically appointed by a frame relay service provider in order to uniquely identifying each virtual circuit that exists on the system network.

From a data transmitter's perspective, information from the end user is changed over to segments. Segments are then passed on to alternate layers and changed over into packets or datagrams. These packets are then changed over into frames before passing on to the system network interface. Where at the end frames are changed over to bits preceding actual information transmission.

There are really five sorts of passwords that can be utilized. These enable secret, virtual terminal, support, and auxiliary.

For a network organization, segmenting a network would enable a network traffic and guarantees that high bandwidth is made accessible constantly for all clients or users. This means better execution, particularly for a developing network.

The hostname and the Interfaces. The hostname is the name of your switch. The Interfaces are settled designs that allude to the switch ports.

Logical Topology alludes to the signal path through the physical topology. Physical Topology is the genuine design of the network medium.

This may happen when the hold-down timer has lapsed, or when the router received a processing task that unexpectedly was relative to the number of links in the internetwork.