The knowledge of networking is the most crucial requirement for every interview often these questions seem to be really easy, but they turn up to be confusing when you go on to answer them. Hey guys, welcome back to a new session from Edureka. My name is Vajija and I'm here to help you answer the 50 most important and commonly asked networking interview questions. So before we begin just make sure you subscribe to our channel and hit the bell icon to stay updated with all the latest edureka videos. So now let's quickly move ahead towards our first question for this session, which is what is the difference between a router a hub and a switch so a hub is basically a device that connects two or more Ethernet devices a switch on the other hand connects two or more devices on the land.
A router can connect devices on LAN man or van. I hope you all are aware of what is LAN man and van LAN basically stands for local area Network man stands for metropolitan area Network and van stands for white area Network hub does not perform many actions such as filtering a switch on the other hand filters packets before forwarding them and a router is highly configured to filter and send packets hub. is the least intelligent least expensive and the least complex device. Whereas a switch is similar to a hub, but it is slightly more effective than the hub. Rooters are extremely smart and complex.
We'll be discussing more about routers in the upcoming questions. So now let's move on towards the next question, which is what exactly is a link a link is basically a connection between two or more computers or devices. It can be anything depending on whether it is a physical connection or a wireless one.
Physical links include cables hubs switches, etc. Whereas wireless links include wireless access points routers, etc. Okay. So now let's move on towards the next question, which is what do you mean by a node guys?
The point of intersection in a network is called as a node nodes can send or receive data or information within a network. For example, if two computers are connected to form a network, there are two nodes in that network. Similarly in case there are three computers, there'll be three notes and so on it is not necessary for a note to be a computer.
It can be any communicating device such as printers servers modems, etc. Okay. So the question that follows is what does a backbone Network mean as we all know in any system a backbone is the most principal component that supports all other components similarly in networking a backbone Network is a network that interconnects various parts of that Network.
to which it belongs. It also has a high capacity connectivity infrastructure and this is because it has to handle a large number of devices or hosts on that network. Okay. So moving on what do you mean by network topology network topology refers to the physical layout of a computer network. It basically gives the design of how the devices are connected within a network.
There are various types of network topologies such as the bus topology start apology ring topology mesh topology tree topology the daisy chain topology hybrid topology and the point-to-point topology in a bus topology. All the devices share a common communication line on the other hand in a star topology all nodes are connected to a central hub device when it comes to the ring topology. Each node connects to exactly two other nodes. The nodes of a mesh topology are connected to one or more other nodes.
The tree topology is also known as a hierarchical topology. It is similar to the star topology and it inherits the bus topology when it comes to daisy chain all nodes are connected linearly in hybrid topology nodes are connected in more than one topology styles. Finally the point-to-point topology is a network that connects exactly two devices such as computers servers, etc.
So moving on towards the next question, which is explain what is LAN LAN as many of us know stands for local area Network. It is the network between devices that are located within a small physical location. It can either be a wireless or wired one land differs from another based on many factors such as topology protocols and the media topology as I've mentioned earlier is the arrangement of nodes within a network.
Protocol basically refers to the rules that govern the transfer of data media refers to the medium that connects the devices these devices can be connected using optic fibers twisted pair wires, etc. Okay. So now moving on towards the next question, which is what exactly are routers a router is some device that transfers the data packets within a network.
It basically performs the traffic directing functions in a given Network. This traffic can include any kind of data packets such as an email webpage Etc. Routers are located at the place where two or more networks meet or at the gateways. They can either be standalone devices or virtual machines standalone routers are traditional devices.
Whereas virtual routers are actually softwares that act like physical ones. So the question that comes next is What exactly is a point-to-point network a point-to-point network refers to a physical connection between two nodes. It can be between any device of a network such as computers printers servers, etc. So for example as you can see on the screen, I have three devices and all these devices are interconnected to each other device.
One is connected to device 2 and device 3 device 2 on the other hand is connected to device 3 and device 1 And finally the device 3 is connected to device 2 and device 1 using physical links. So I hope you all have got an idea of what exactly is a point-to-point Network. Okay.
So now let's move on towards the next very important question, which is what is the OSI model OSI actually stands for open systems interconnection. It is a conceptual model that standardizes the communication functions of telecommunication. It basically has seven layers which starts from the physical layer.
followed by the data link layer network layer transport layer the sessions layer the presentation layer and finally the application layer the three lower level layers are the hardware layers, which is the physical layer the data link layer and the network layer the transport layer is also called as the heart of the OSI model the three upper layers which constitute the OSI model namely the sessions layer. The presentation layer and the application layer are also called as software layers of this model. So for more details about this, let's move on towards our next question, which is give a brief about each layer in the OSI model. Okay.
So as we all know the low most layer of the OSI model is the physical layer. It makes use of the symbol protocol and it transfers raw bits of data over a physical link. Next is the data link layer. The data link layer follows the frame protocols.
It is basically reliable transmission of data frames between nodes connected by the physical layer. So as you can see over here the physical layer was actually transmitting bits of data over a physical link, but the data link layer is transmitting data frames between nodes. So up next is the network layer the network layer follows the packet protocols.
This layer structures and manages a network with multiple nodes including addressing routing and traffic control at the mid of the OSI model lies the transport layer the transport layer follows the segment and the datagram protocols. It provides reliable transmission of data packets between different points of a network the layer that sits on top of the transport layer is the sessions layer sessions layer follows the data protocols and it manages the communication sessions. Above that is the presentation layer the presentation layer also follows the data protocols. It provides transmission of data between service device and the application the service device can be anything such as a server and the application basically refers to the client finally at the topmost position lies the application layer this layer also follows the data protocols and it specifies the shared communication protocols and interface methods. Okay.
So with this I hope you guys have got an idea of what exactly is the OSI model and what the various layers are responsible for so now moving on towards the next question, which is what do you mean by an anonymous FTP and anonymous FTP is a way of allowing a user to access data that is public the user does not need to identify himself to the server and has to log in as anonymous. So in case if you are asked to use some anonymous FTP, make sure you add anonymous in place of your user ID anonymous FTPs are very effective while distributing large files to a lot of people and that without having to give huge numbers of usernames and password combinations. So up next is a very important question, which is what do you mean by a network a network is a connection between different devices.
These devices communicate with each other using physical or wireless connections physical connections include twisted pair cables optic fibers and coaxial fibers wireless networks can be established with the help of waves such as radio waves infrared waves and microwaves networks basically serve many purposes such as sharing hardware devices such as printers input devices Etc. They also help in communications in many ways such as audios videos emails messages Etc networks also help in sharing data and information using virtual devices last but not the least they also help sharing softwares that are installed on other devices. So now moving on towards the next question, which is what do you mean by a subnet mask a subnet mask is a number describing the range of IP addresses that can be used within a network. They are used to assign sub networks or subnets.
These sub networks are various lands connected to the internet this subnet mask is basically a 32-bit number and it masks the IP address and then divides the IP address into two parts that is the network address and the host address subnet masks are created by setting all the network bits to one and all the host bits to zero. There are two network addresses that cannot be assigned to any host that is 0 and 225 0 is assigned to the network and 225 is assigned to the broadcast address and this is the reason why they cannot be assigned to any other host. So now moving on towards the next question, which is give a brief description of the TCP IP model.
The TCP IP model is a compressed version of the OSI model. It stands for transmission control protocol internet protocol. and was designed and developed in 1960s by the Department of Defense.
This model contains four layers. Unlike the OSI model, which are process or the application layer the host to host or the transport layer the internet layer or the network layer and finally the network access layer, which is a combination of the physical and the data link layers the network layer basically looks after the hardware addressing the protocols present in the network layer allow you to transmit data physically. Talking about the internet layer it corresponds to the functions of the network layer in the OSI model.
Its protocols define rules for logical transmission of data over the complete network. The main protocols that comprise the internet layer are IP, ICMP and ARP IP stands for internet protocol. The IP protocol delivers data packets from the host to the destination by looking at the IP addresses that are present in the packet headers. There are two versions of the IP protocol namely IPv4 and IPv6.
IPv4 is the older version and most of the websites today make use of this IPv6 is the latest version the number of IPv4 addresses are quite limited in comparison to the number of hosts using them. IPv6 provides a hundred and twenty eight bit IP address number. Therefore it solves the issue of limited addresses. So talking about ICMP ICMP stands for internet control message protocol.
This protocol is encapsulated within the IP datagrams. Its responsibility is to provide hosts with the network problems information ARP stands for address resolution protocol. The main job of this protocol is to find the hardware address of the host from a given IP address ARP can also be of many types such as reverse ARP proxy ARP inverse ARP, etc. Okay. The host to host layer this layer of the TCP IP model corresponds to the transport layer of the OSI model.
Its responsibility is to provide end-to-end communication and error-free delivery of the data that is being transmitted. It basically shields the upper layer applications from complexities of data the two main protocols that are used within this layer are the TCP or the transmission control protocol and the UDP or the user datagram protocol. TCP is known to provide reliable and error-free communication between end systems UDP.
On the other hand is a go-to protocol. If your application does not require reliable transport finally is the process layer. This layer performs all the functions of the top three layers of the OSI model, which are the application layer the presentation layer and the sessions layer it is responsible for node-to-node communication and controls user interface specifications.
The protocols that are used in this layer are HTTP, HTTPS, FTP, TFTP, telnet, SSH, etc. So now let's move on towards our next question, which is what is the difference between the OSI model and the TCP IP model as we've already discussed the OSI model has seven layers and the TCP IP model has four layers. The TCP IP model is more reliable compared to the OSI model. and it has no strict boundaries the OSI model on the other hand has strict boundaries and the approach that it follows is the vertical approach the TCP IP model follows a horizontal approach in contrast. So these were a few differences between these two models.
However, there are many more which you can explore for yourself. So now moving on towards the next question, which is what is a UTP cable a UTP cable is a hundred ohms cable made up of copper. It consists of two to 1800 unshielded twisted pairs that are surrounded by non-metallic case these twists actually provide immunity to electrical noise and EMI.
Okay. So what is the maximum length that can be allowed for a UTP cable the maximum length that is allowed for a UTP cable is 100 meters. This includes 90 meters of solid cabling and 10 meters of standard patch cable. Okay.
So up next explain what is HTTP and which port does it use? HTTP or the hypertext transfer protocol allows communication over the internet this protocol basically defines how messages are to be transmitted. and formatted over the world wide web. HDP is a TCP IP protocol and it uses both number 80 some of the features of this protocol are it is connection. Less does not depend on the type of connecting media and it's also stateless.
Okay, so moving on towards the next question. What exactly is n80 guys and 80 stands for network address translation. It deals with remapping IP address space with another by changing the IP headers of packets that are being transmitted across a traffic routing device because of this capability and 80 can be configured to advertise only one address for the entire network to the outside world.
This in turn provides extra security as it effectively hides the whole internal network behind the specific address. So an 80 offers two functions that is of security and of address conversion. Nat is typically used in remote access environments.
So moving on towards the next question, which is what is TCP TCP stands for transmission control protocol. It is a connection oriented protocol that establishes and maintains a connection between communicating devices until both of them are done exchanging messages. This protocol determines how application data can be broken down into packets that can be delivered over a network. It also sends and receives packets to and from the network layer and it's in charge of the flow control Etc. Okay.
So up next is give a brief explanation about UDP UDP stands for user datagram protocol. It is used to create a low latency and a loss tolerating communication between applications connected over the internet UDP enables process-to-process communication and communicates via datagrams or messages. The user datagram protocol has some remarkable features that make it very effective to use along with applications that can manage loss of data UDP allows the packets to be dropped and received in a different order than that in which they were transmitted. This makes it suitable for real-time applications wherein latency might sometimes be a concern UDP can also be used in transmission based protocols such as DNS or the network time protocol.
It can be used in situations where a huge number of clients are interconnected and also in situations where real-time error correction isn't very important. This is the case in applications such as gaming voice or video conferencing and streaming media. So the question that follows is what is the difference between TCP and UDP by now? I think you have a basic idea of what is TCP and UDP.
So moving on to differentiate between them. I'll be considering a few factors for comparison. The first is connection when you're using the TCP protocol connections are made before the application messages are exchanged on the other hand UDP connections are not made before the application messages are actually exchanged.
The second difference is based on the use TCP protocols are used for applications needing more reliability and less speed whereas UDP is used for applications needing more speed and less reliability. Okay, so talking about the use by protocols of the application layer TCP IP deals with file transfer emails, etc. Whereas UDP deals with multimedia and DNS.
So talking about the reliability in the TCP protocol messages will be delivered in order and without any errors on the other hand. The UDP has no guarantee that the messages will be delivered in order and without errors. So moving on towards the next difference, which is based on data segments. The TCP data segments can be rearranged in the required order.
Whereas in the UDP protocol all segments are independent and therefore it has no inherent order of specification. The TCP protocol consists of acknowledgments whereas the UDP protocol does not consist of them flow control TCP has the congestion control mechanism, but UDP on the other hand has no flow control options. So the final comparison factor is checking for errors the TCP protocol recents erroneous segments. Whereas the UDP protocol discards erroneous segments. So I hope you're clear with the difference between these two.
Okay. So now let's move on towards the next question, which is what exactly is our IP our IP stands for routing information protocol. It is a dynamic routing protocol and it makes use of hop count as its primary metric to find the best part between source and the destination. It works in the application layer and it has an ad or the administrative distance value of 120 some of the key features of our IP are It periodically exchanges updates of the network these updates or routing information is always broadcast not just that complete routing tables are sent within these updates as well routers basically trust on routing information received from the neighboring routers and this is also known as rooting on rumors. Okay.
So next up is a very important question, which is what exactly is a firewall? A firewall as its name says is a network security system, which is used to monitor and control the network traffic based on some predefined rules firewalls are the first line of defense and establish barriers between internal and external networks in order to avoid attack from untrusted external networks. These firewalls can either be hardware's software's or sometimes both. So moving on towards the next question, which is explain what is nos. NOS stands for network operation system.
It is an operating system that is designed to support workstations databases personal computers, etc over a network some examples of NOS are the Mac OS X Linux Windows Server 2008 Etc. These operating systems provide various functionalities such as processor support multi-processing support authentication web services Etc. So now moving on towards the next question, which is explain what is denial of service denial of service or DOS is a kind of attack that prevents a legitimate user from accessing data over a network by a hacker or an attacker the attacker floods the server with unnecessary requests in order to overload the server thereby preventing the legitimate users from accessing its services. Okay, so moving on what is the full form of ASCII? ASCII stands for American Standard Code for information interchange.
It is a character encoding standard used in the electronic communication field and the ASCII codes basically represent text ASCII was developed from telegraph code its first commercial use was in a 7-bit teleprinter code promoted by Bell data services ASCII code order is also called as the ASCII medical order collation. or assembling written information in a standard order of data is sometimes done in this order than in the standard alphabetical order the main deviations in the ASCII order are all uppercase letters come before the lowercase letters. So for example a caps a will precede a small a digits and many other punctuation marks will come before the letters and intermediate order converts uppercase letters to the lowercase letters before comparing the ASCII values. So now moving on towards the next question, which is what exactly is I Tripoli I Tripoli as many of us know stands for Institute of electrical and electronics engineer. It is the world's largest technical professional Society and it is devoted to advancing innovation and technological excellence.
It was originally formed in 1963 from the Coalition of American Institute of electrical engineers and the Institute of radio engineers today. It has more than 4 lakh 23,000 members in over 160 countries all over the world. Okay. So now moving on towards the next question, which is what is Mac address and why is it required Mac or the media access control address is a computer's unique number assigned to a network interface controller. It is a 48-bit number that identifies each device on a network and it is also referred to as the physical address.
MAC addresses are used as a network address for communications within a network such as Ethernet Wi-Fi, etc. Okay. So up next is what is piggybacking during transmission of data packets in the two-way communication the receiver sends an acknowledgement or the control frame are also called as ACK to the receiver after receiving the data packets. However, the receiver does not send the acknowledgement immediately, but it waits until its network layer passes in the next data packet. Then the acknowledgement is attached to the outgoing data frame this process of delaying the acknowledgement and attaching it to the next outgoing data frame is known as piggybacking.
Okay, so moving on explain. What is DNS DNS stands for domain name system. It is a naming system for devices connected over the internet.
It is a hierarchical and decentralized system that translates domain names to numerical IP addresses, which is required to identify and locate devices based on the underlying protocols all devices connected to the internet have unique IP addresses which are used to locate them on the network. This process involves conversion of host names into IP addresses. So for example, In case the user wants to load some web page say xyz.com this host name is converted into an IP address that can be understood by the computer in order to load that web page. So now moving on towards the next question, which is the difference between domain and a workgroup domains have one or more computers that act as a server whereas workgroup consists of computers that are peers domains have centralized databases. Whereas in workgroups.
Each computer has its own database domain computers can be on different lands. Whereas in the work group all computers are on the same land. So now let's move on towards the next question, which is what exactly is OSPF OSPF stands for open shortest path first.
It is basically a routing protocol that is used to find the best path for packets that are being transmitted over interconnected networks OSPF is commonly used in IGP. or interior Gateway protocol in huge Enterprise networks. It basically implements the diktra's algorithm, which is also known as the shortest part first algorithm as a link state rooting protocol.
It was based on the link state algorithm developed for the arpanet in 1980 and the is is rooting protocol. Okay. So now moving on towards the next question, which is what is round-trip time? Round-trip time or round-trip delay time refers to the time taken for a signal to be sent and the acknowledgement of that signal to be received.
This includes the propagation times for the paths between the two communicating hosts. So up next what is DHCP DHCP or dynamic host configuration protocol is a network management protocol. It is used on the UDP IP networks and it automatically assigns IP addresses to devices on the network.
This in turn reduces the need of a network admin to manually assign IP addresses thereby reducing errors DHCP can be used on networks ranging in any size. That is from home networks to large computer networks as well as regional internet service providers a router or a residential Gateway can be attached which will act as a DHCP server. Most of the residential network routers get a globally unique IP address within the ISP network.
in local networks a DHCP server assigns a local IP address to every device that is connected to the network. So now moving on towards the next question, which is briefly explain. What is ICMP ICMP stands for internet control message protocol and it is a part of the internet protocol suit. It is basically a supporting protocol to the internet protocol. and it's used to send error messages and information regarding the success or failure of communication with some IP address.
So for example, if a service is not available and error is going to be reported. Okay. So now moving on towards the next very important question, which is what exactly is ping a ping is a computer program that is used to test the reachability of a host and check if it can accept requests on an IP network. It works by sending an ICMP or the internet control message protocol echo to some computer on the network and it waits for a reply from it.
Not just this it can also be used for troubleshooting. So what are the advantages of using optic fibers as many of us know optic fibers have a number of advantages such as it has greater bandwidth than other metal cables. It has low power loss which allows longer transmission distances.
Optic cables are also immune to electromagnetic interference. They have lesser production rates their thin and light optic fiber cable is difficult to tap. So moving on towards the next very important question, which is what is a client server Network a client server Network is a network where one computer behaves as a server to the other computers.
The server is usually more powerful than the clients and it's used to serve the clients these clients and servers usually communicate over a computer network on separate hardware, but both the client and the server can reside on the same system as well. The server is a host that runs one or more server processes which share their resources with clients who request for them a client basically does not share any of its resources, but it can request for information or services from the server. Clients therefore initiate the communication with servers whereas the server waits for the incoming request some example of the client server model are the emails network printing and World Wide Web.
Okay. So now moving on towards the next tricky question, which is in a network that contains two servers and 20 workstations. Where is the best place to install an antivirus program?
The best solution is to install antivirus on all the computers in that Network. This will protect each device from the other in case some malicious user tries to insert a virus into the servers or the legitimate users. Okay, so moving on what do you mean by Ethernet Ethernet is a network technology that is used in local area networks metropolitan area networks as well as wide area networks this connects devices using cables for the transmission of data. It provides services on the physical and the data link layers of the OSI model Ethernet was initially based on the idea of hosts communicating over shared coaxial cable that acts as a broadcast transmission medium and this shared coaxial cable traversed a small area such as a building or a campus and to every attached host today. Ethernet is widely used in homes as well as Industries.
The internet protocol is usually carried over Ethernet and therefore it's considered as one of the the key Technologies that build up the internet. So now moving on towards the next question. What exactly is slip slip stands for serial line internet protocol which allows a user to access the internet using the modem slip is an encapsulation of the internet protocol that is designed to work over series of ports and router connections slip modifies the standard TCP IP datagram by performing a few changes that are appending an extra end byte or the frame and byte to the datagram which is used to distinguish between datagram boundaries in the byte stream in case that n byte occurs in the data to be sent the two byte sequences, which is frame escape and transposed frame end is sent instead if the frame escape byte occurs in the data the two byte sequence frame escape and transposed frame escape is sent instead. Variants of the protocol may begin or end with packets with the end byte.
So now moving on towards the next question, which is what is the difference between CSM a CD and CSM ACA CSM a CD basically stands for carrier sense multiple-axis collision detection. It is a set of rules determining how network devices respond when two devices try to use the data channel at the same time and this is also called as collision. CSMACA stands for carrier sense multiple access with collision avoidance. It is a network multiple access method in which the carrier sensing is used but nodes attempt to avoid collisions. This is done by beginning the transmission only of the channel is idle.
Okay. So the key differences between these two are CSMACD comes into effect after a collision. On the other hand CSMA CA is designed to come into effect before a collision actually occurs CSMA CD minimizes the recovery time whereas CSMA CA reduces the possibility of the collision itself CSMA CD usually occurs in wired networks and on the other hand CSMA CA is usually used in Wireless networks.
So there are many other differences which you guys can explore for yourself. So moving on towards the next question, which is Let's briefly explain. What is the tunnel mode tunnel mode is actually used to encrypt the whole IP packet including the headers and the payload. It is basically used in site-to-site VPN to secure communications between security gateways firewalls, etc. Okay.
So what do you mean by ipv6 ipv6 stands for internet protocol version 6 and it is the latest version of internet protocol. Hosts on the internet are assigned a unique IP address for identification and to locate them with the rapid growth of internet. It became evident that we need more addresses to connect hosts over the internet than the IPV for address space provides in IPV 6. The IP address length is 128 bits which resolves the issue of approaching shortage of network addresses.
IPv6 also provides other benefits in addition to this such as it permits hierarchical address allocation methods that provide root aggregation over the internet and thus limit the expansion of routing tables. Also the use of multicast addressing is expanded and made simpler this provides additional optimization for the delivery of services IPv6 also provides other benefits such as security configuration and device mobility. So now moving on towards the next very important question, which is explained the RSA algorithm briefly RSA is a crypto system used to secure data transmission and it's named after Ron Rivas to add the Shamir and Len Edelman this algorithm has a public key for encryption while the decryption key is kept secure or private the encryption key is created using two large prime numbers and it's published along with an auxiliary value.
Anybody can make use of this public key for encryption, but only someone with the knowledge of the prime numbers can decrypt it. However, this algorithm is considered to be slow and for the same reason it is not used very often to encrypt data. So now moving on towards the next question, which is what exactly is an encoder an encoder is a program circuit or a device that converts data from one format to another.
Encoders basically convert analog signals into digital ones. So now that you know, what is an encoder? Let's move on and see what is decoder a decoder is a program circuit or a device that converts encoded data into its actual format decoders unlike encoders convert digital signals to analog ones. Okay, so moving on towards the next question, which is what is sneaker net?
Sneaker net is the unofficial term for the transfer of electronic information by physically moving media, which can be anything such as a floppy disk USB flash optical discs Etc. So now moving on towards the last question of this session, which is what are the components of a protocol protocols are basically a set of rules that govern communication the key elements of a protocol are syntax semantics and timing syntax refers to the structure and format of data. whereas semantics refer to the meaning of each portion of bits. Timing refers to when data should be sent and received.
So this brings us to the end of this session. I hope you guys have enjoyed and learn something new. Make sure to practice as much as possible and in case you have any doubts or queries, please do let me know in the comment section and I will revert to you at the earliest. Goodbye and take care.
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