Hello friends, today we will discuss Top 10 interview questions on OSI model.
Q1. Define OSI layers.
Ans: OSI stands Open System Interconnection. There are 7 layers in OSI model. OSI model helps networking professional in understanding information flow from one source to destination. Although, OSI model not performing any function in the networking process.
Q2. Are there any alternative models to the OSI model? If yes, define it.
Ans: TCP/IP is the alternate model that also explains the information flow in the network. It is simpler representation in comparison to OSI model but contains fewer details of protocols than OSI model.
Q3. What is the difference between TCP and UDP?
Ans: TCP and UDP: Comparison between Two Transport Protocols
|Acronym||Transmission Control Protocol||User Datagram Protocol|
|Connection||Connection Oriented Protocol||Connection Less Protocol|
|Function||Message transfer from source to destination in an ordered and error-checked stream.||Message transfer from one point to another without checking any order and any error in the stream.|
More transmission time
Less transmission time
|Reliability||Guarantee Data transfer and arrives in the same order in which it was sent.||No guarantee that the messages or all packets sent would reach from source to destination.|
|Other protocols||HTTP, HTTPs, FTP, SMTP, Telnet||DNS, DHCP, TFTP, SNMP, RIP, VOIP|
|Header size||TCP header size is 20 bytes||UDP header size is 8 bytes|
|Headers||Fields in TCP Header|
1. Sequence Number,
2. AcK number,
3. Data offset,
5. Control bit,
7. Urgent Pointer
11. Source port,
12. Destination port
|Fields in UDP Header|
|Handshake||Three-way handshake||No handshake|
|Data Flow Control||It controls the flow of data||Does not have an option for flow control of data|
Q4. What is the importance of the Physical Layer in OSI model?
Ans: Physical layer resembles actual transfer of information from source to destination in form of bit stream – electrical impulse, light or radio signal. In simple words, it accepts a frame from data link layer and converts it into bits. Also accepts bits from physical medium and convert it into the frame.
Common protocols for this layer are EIA/TIA-232, EIA/TIA-449, X.21, HSSI, V.24, V.35, and SONET.
Q5. Which layers perform error detection and flow control?
Ans: On receiving and while transmission of information, Layer 2 – Data Link layer decoded and encoded data into bits. The data link layer is further divided into two sublayers: The Media Access Control (MAC) layer and the Logical Link Control (LLC) layer. This layer also performs error checking and flow control.
Q6. How the network administrator detect the problem?
Ans: Network Administrator use OSI model to understand the information flow and try to find problems by further understand the protocols of each layer. Experience in networking reduces the time to find problems and resolve them. Network problems may be a loose physical connection, configuration issues etc.
Q7. What is the difference between flow control and error control?
Ans: As the name suggests, flow control controls the rate of information transmitted to ensure efficient delivery of data to the receiver. While error control checks and correct errors in the data bits and packets.
Q8. What is Data encapsulation?
Ans: Data encapsulation is a process of adding extra information at each layer of OSI model while information flow from one host to another host. Information such as source and destination address, protocol information, type of data etc.
Q9. What are the differences between MAC sublayer and LLC sublayer?
Ans: MAC sublayer stands for Media Access Control layer. MAC address works on Layer 2- Data Link Layer. This layer controls the permission of data to transmit it.
LLC sublayer stands for Logical Link Control layer. This layer controls frame synchronization, flow control, and error checking.
Q10. What is the difference between half-duplex and full-duplex?
Ans: In half-duplex, information can flow in both direction but not simultaneously. While in full-duplex, information can flow in both directions simultaneously.
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Disclaimer: This tutorial is for educational purpose only. Individual is solely responsible for any illegal act.