Latest Network Engineering Interview Questions Part – 4
Q – 71 Explain sliding window?
Ans- The sliding window is an abstract concept that defines the range of sequence numbers that is the concern of the sender and receiver. In other words, he sender and receiver need to deal with only part of the possible sequence numbers.
Q – 72 Explain the usage of sequence number in relaible transmission?
Ans- The protocol specifies that frames need to be numbered. This is done by using sequence numbers. A field is added to the data frame to hold the sequence number of that frame. Since we want to minimize the frame size, the smallest range that provides unambiguous communication. The sequence numbers can wrap around.
Q – 73 Explain stop-and-wait automatic repeat request?
Ans- Error correction in Stop-and-Wait ARQ is done by keeping a copy of the sent frame and re-transmitting of the frame when the timer expires.
Q – 74 Explain stop-and-wait protocol?
Ans- In Stop and wait protocol, sender sends one frame, waits until it receives confirmation from the receiver (okay to go ahead), and then sends the next frame.
Q – 75 Describe automatic repeat request (ARQ)?
Ans- Error control is both error detection and error correction. It allows the receiver to inform the sender of any frames lost or damaged in transmission and coordinates the re-transmission of those frames by the sender. In the data link layer, the term error control refers primarily to methods of error detection and re-transmission. Error control in the data link layer is often implemented simply: Any time an error is detected in an exchange, specified frames are re-transmitted. This process is called automatic repeat request (ARQ).
Q – 76 Describe error control?
Ans- Error control is both error detection and error correction. It allows the receiver to inform the sender of any frames lost or damaged in transmission and coordinates the re-transmission of those frames by the sender. In the data link layer, the term error control refers primarily to methods of error detection and re-transmission.
Q – 77 Describe flow control?
Ans- Flow control refers to a set of procedures used to restrict the amount of data that the sender can send before waiting for acknowledgment.
Q – 78 Describe bit stuffing?
Ans- Bit stuffing is the process of adding one extra 0 whenever five consecutive Is follow a 0 in the data, so that the receiver does not mistake the pattern 0111110 for a flag.
Q – 79 What is character stuffing?
Ans- In byte stuffing (or character stuffing), a special byte is added to the data section of the frame when there is a character with the same pattern as the flag. The data section is stuffed with an extra byte. This byte is usually called the escape character (ESC), which has a predefined bit pattern. Whenever the receiver encounters the ESC character, it removes it from the data section and treats the next character as data, not a delimiting flag.
Q – 80 Describe fixed size framing?
Ans- In fixed-size framing, there is no need for defining the boundaries of the frames. The size itself can be used as a delimiter.
Q – 81 Explain framing?
Ans- Framing in the data link layer separates a message from one source to a destination, or from other messages to other destinations, by adding a sender address and a destination address. The destination address defines where the packet has to go and the sender address helps the recipient acknowledge the receipt.
Q – 82 What is Decoder?
Ans- Decoder is A device or program that translates encoded data into its original format (e.g. it decodes the data). The term is often used in reference to MPEG-2 video and sound data, which must be decoded before it is output.
Q – 83 What is Encoder?
Ans- A device or program that uses predefined algorithms to encode, or compress audio or video data for storage or transmission use. A circuit that is used to convert between digital video and analog video.
Q – 84 Explain cyclic codes?
Ans- Cyclic codes are special linear block codes with one extra property. In a cyclic code, if a code-word is cyclically shifted (rotated), the result is another code-word.
Q – 85 Explain linear block code?
Ans- A linear block code is a code in which the exclusive OR (addition modulo-2) of two valid code-words creates another valid code-word.
Q – 86 Explain code words?
Ans- “r” redundant bits are added to each block to make the length n = k + r. The resulting n-bit blocks are called code-words. 2n – 2k code-words that are not used. These code-words are invalid or illegal.
Q – 87 Explain data words?
Ans- In block coding, we divide our message into blocks, each of k bits, called data-words. The block coding process is one-to-one. The same data-word is always encoded as the same code-word.
Q – 88 What is retransmission?
Ans- A technique in which the receiver detects the occurrence of an error and asks the sender to resend the message. Re-sending is repeated until a message arrives that the receiver believes is error-freed.
Q – 89 Explain forward error correction?
Ans- Forward error correction is the process in which the receiver tries to guess the message by using redundant bits.
Q – 90 Can you please explain the difference between error detection and error correction?
Ans- The correction of errors is more difficult than the detection. In error detection, checks only any error has occurred. In error correction, the exact number of bits that are corrupted and location in the message are known. The number of the errors and the size of the message are important factors.
Q – 91 Explain data link protocols?
Ans- Data link protocols are sets of specifications used to implement the data link layer.
The categories of Data Link protocols are:
1. Asynchronous Protocols
2. Synchronous Protocols
☛ Character Oriented Protocols
☛ Bit Oriented protocols
Q – 92 What steps involved in creating the checksum?
Ans-
☛ Divide the data into sections
☛ Add the sections together using 1’s complement arithmetic
☛ Take the complement of the final sum, this is the checksum.
Q – 93 What are error detection methods?
Ans-
The common Error Detection methods are:
☛ Vertical Redundancy Check (VRC)
☛ Longitudinal Redundancy Check (VRC)
☛ Cyclic Redundancy Check (VRC)
☛ Checksum
Q – 94 Explain error detection?
Ans- Data can be corrupted during transmission. For reliable communication errors must be deducted and Corrected. Error Detection uses the concept of redundancy, which means adding extra bits for detecting errors at the destination.
Q – 95 Explain redundancy?
Ans- The concept of including extra information in the transmission solely for the purpose of comparison. This technique is called redundancy.
Q – 96 What is VRC?
Ans- VRC is the most common and least expensive mechanism for Error Detection. In VRC, a parity bit is added to every data unit so that the total number of 1s becomes even for even parity. It can detect all single-bit errors. It can detect burst errors only if the total number of errors in each data unit is odd.
Q – 97 What is LRC?
Ans- A block of bits is divided into rows and a redundant row of bits is added to the whole block. It can detect burst errors. If two bits in one data unit are damaged and bits in exactly the same positions in another data unit are also damaged, the LRC checker will not detect an error. In LRC a redundant data unit follows n data units.
Q – 98 What is CRC?
Ans- The most powerful of the redundancy checking techniques, is based on binary division.
Q – 99 What is checksum?
Ans- Used by the higher layer protocols (TCP/IP) for error detection.
Q – 100 Explain the types of errors?
Ans-
☛ Single-Bit error:
In a single-bit error, only one bit in the data unit has changed
☛ Burst Error:
A Burst error means that two or more bits in the data have changed.
Q – 101 Tell me the categories of transmission media?
Ans-
☛ Guided Media:
1: Twisted – Pair cable
a: Shielded TP
b: Unshielded TP
2: Coaxial Cable
3: Fiber-optic cable
☛ Unguided Media:
1: Terrestrial microwave
2: Satellite Communication
Q – 102 Tell me the different link types used to build a computer network?
Ans-
☛ Cables
☛ Leased Lines
☛ Last-Mile Links
☛ Wireless Links
Q – 103 What are the two classes of hardware building blocks?
Ans- Nodes and Links.
Q – 104 List the the responsibilities of Application Layer?
Ans- The Application Layer enables the user, whether human or software, to access the network. It provides user interfaces and support for services such as e-mail, shared database management and other types of distributed information services.
☛ Network virtual Terminal
☛ File transfer, access and Management (FTAM)
☛ Mail services
☛ Directory Services
Q – 105 List the responsibilities of Presentation Layer?
Ans- The Presentation layer is concerned with the syntax and semantics of the information exchanged between two systems.
☛ Translation
☛ Encryption
☛ Compression
Q – 106 List the responsibilities of session layer?
Ans- The Session layer is the network dialog Controller. It establishes, maintains and synchronizes the interaction between the communicating systems.
☛ Dialog control
☛ Synchronization
Q – 107 List the responsibilities of Transport Layer?
Ans-
The Transport Layer is responsible for source-to-destination delivery of the entire message.
☛ Service-point Addressing
☛ Segmentation and reassembly
☛ Connection Control
☛ Flow Control
☛ Error Control
Q – 108 List the responsibilities of Network Layer?
Ans- The Network Layer is responsible for the source-to-destination delivery of packet possibly across multiple networks (links).
☛ Logical Addressing
☛ Routing
Q – 109 List the responsibilities of data link layer?
Ans- The Data Link Layer transforms the physical layer, a raw transmission facility, to a reliable link and is responsible for node-node delivery.
☛ Framing
☛ Physical Addressing
☛ Flow Control
☛ Error Control
☛ Access Control
Q – 110 List the concerns of the physical layer?
Ans- Physical layer coordinates the functions required to transmit a bit stream over a physical medium.
☛ Physical characteristics of interfaces and media
☛ Representation of bits
☛ Data rate
☛ Synchronization of bits
☛ Line configuration
☛ Physical topology
☛ Transmission mode
Q – 111 What layer links the network support layers and user support layers?
Ans- The Transport layer links the network support layers and user support layers.
Q – 112 What layers are user support layers?
Ans-
☛ Session Layer
☛ Presentation Layer and
☛ Application Layer
Q – 113 What layers are network support layers?
Ans-
☛ Physical Layer
☛ Data link Layer and
☛ Network Layers
Q – 114 What are the layers of OSI?
Ans-
☛ Physical Layer
☛ Data Link Layer
☛ Network Layer
☛ Transport Layer
☛ Session Layer
☛ Presentation Layer
☛ Application Layer
Q – 115 Explain synchronous TDM?
Ans- In STDM, the multiplexer allocates exactly the same time slot to each device at all times, whether or not a device has anything to transmit.
Q – 116 What is TDM?
Ans- Digital process that can be applied when the data rate capacity of the transmission medium is greater than the data rate required by the sending and receiving devices.
Q – 117 What is WDM?
Ans- WDM is conceptually the same as FDM, except that the multiplexing and de-multiplexing involve light signals transmitted through fiber optics channel.
Q – 118 What is FDM?
Ans- FDM is an analog technique that can be applied when the bandwidth of a link is greater than the combined bandwidths of the signals to be transmitted.
Q – 119 List the categories of multiplexing?
Ans-
☛ Frequency Division Multiplexing (FDM)
☛ Time Division Multiplexing (TDM)
1: Synchronous TDM
2: ASynchronous TDM Or Statistical TDM.
☛ Wave Division Multiplexing (WDM)
Q – 120 Explain multiplexing?
Ans- Multiplexing is the set of techniques that allows the simultaneous transmission of multiple signals across a single data link.
Q – 121 What is broadcasting in network engineering?
Ans- If the message is sent to all the m nodes in the network it is called Broadcasting.
Q – 122 What is multiccasting in network engineering?
Ans- If the message is sent to some subset of other nodes, it is called Multicasting.
Q – 123 What is unicasting in network engineering?
Ans- If the message is sent from a source to a single destination node, it is called Uni-casting.
Q – 124 Explain Round Trip Time?
Ans- The duration of time it takes to send a message from one end of a network to the other and back, is called RTT.
Q – 125 Explain semantic gap?
Ans- Defining a useful channel involves both understanding the applications requirements and recognizing the limitations of the underlying technology. The gap between what applications expects and what the underlying technology can provide is called semantic gap.
Q – 126 List the key elements of protocols?
Ans-
The key elements of protocols are:
☛ Syntax:
It refers to the structure or format of the data, that is the order in which they are presented.
☛ Semantics:
It refers to the meaning of each section of bits.
☛ Timing:
Timing refers to two characteristics: When data should be sent and how fast they can be sent.
Q – 127 Tell me the key design issues of a computer Network?
Ans-
☛ Connectivity
☛ Cost-effective Resource Sharing
☛ Support for common Services
☛ Performance
Q – 128 Explain routing?
Ans- The process of determining systematically hoe to forward messages toward the destination nodes based on its address is called routing.
Q – 129 Can you please explain the difference between Bandwidth and Latency?
Ans- Network performance is measured in Bandwidth (throughput) and Latency (Delay). Bandwidth of a network is given by the number of bits that can be transmitted over the network in a certain period of time. Latency corresponds to how long it takes a message to travel from one end off a network to the other. It is strictly measured in terms of time.
Q – 130 Explain a peer-peer process?
Ans- The processes on each machine that communicate at a given layer are called peer-peer process.
Q – 131 What do you know when a switch is said to be congested?
Ans- It is possible that a switch receives packets faster than the shared link can accommodate and stores in its memory, for an extended period of time, then the switch will eventually run out of buffer space, and some packets will have to be dropped and in this state is said to congested state.
Q – 132 What factors which affect the security of the network?
Ans-
☛ Unauthorized Access
☛ Viruses
Q – 133 What factors that affect the reliability of the network?
Ans-
☛ Frequency of failure
☛ Recovery time of a network after a failure
Q – 134 What are the factors that affect the performance of the network?
Ans-
☛ Number of Users
☛ Type of transmission medium
☛ Hardware
☛ Software
Q – 135 Tell me the criteria necessary for an effective and efficient network?
Ans-
☛ Performance:
It can be measured in many ways, including transmit time and response time.
☛ Reliability:
It is measured by frequency of failure, the time it takes a link to recover from a failure, and the network’s robustness.
☛ Security:
Security issues includes protecting data from unauthorized access and viruses.
Q – 136 Describe the advantages of distributed processing?
Ans-
☛ Security/Encapsulation
☛ Distributed database
☛ Faster Problem solving
☛ Security through redundancy
☛ Collaborative Processing
Q – 137 Tell us multiple access?
Ans- If the physical links are shared by more than two nodes, it is said to be Multiple Access.
Q – 138 Explain point-point link?
Ans- If the physical links are limited to a pair of nodes it is said to be point-point link.
Q – 139 Explain a gateway or Router?
Ans- A node that is connected to two or more networks is commonly called as router or Gateway. It generally forwards message from one network to another.
Q – 140 What is node?
Ans- A network can consist of two or more computers directly connected by some physical medium such as coaxial cable or optical fiber. Such a physical medium is called as Links and the computer it connects is called as Nodes.
Q – 141 Explain Link?
Ans- At the lowest level, a network can consist of two or more computers directly connected by some physical medium such as coaxial cable or optical fiber. Such a physical medium is called as Link.
Q – 142 What is network?
Ans- A network is a set of devices connected by physical media links. A network is recursively is a connection of two or more nodes by a physical link or two or more networks connected by one or more nodes.