The document discusses the OSI model, which consists of seven layers that facilitate understanding of information flow in networking, though it does not perform functions itself. It compares the OSI model with the simpler TCP/IP model, outlines differences between TCP and UDP protocols, and explains the importance of the physical layer. Additionally, it covers network problem detection, error detection and recovery functions, data encapsulation, and the distinction between half-duplex and full-duplex communications.

1. Interview Questions &
Answers
OSI Model
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2. Q. Define OSI layers.
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.
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3. Q. Are there alternative models to the
OSI model? If yes, define it.
• 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.
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4. Q. What are the differences between
TCP and UDP?
Following are differences in TCP and UDP,
• TCP is connection oriented protocol while UDP is
connectionless protocol.
• TCP is more reliable than UDP.
• UDP is faster for data sending than TCP.
• UDP makes error checking but no reporting but TCP makes
checks for errors and reporting.
• TCP provides guaranteed Delivery of Data but UDP has no
guarantee.
• Header size of TCP is 20 bytes while that of UDP is 8 bytes.
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5. Q. What is the importance of the OSI
Physical Layer?
• 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
convert 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.
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6. Q. Which layers perform error
detection and recovery functions?
• 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.
• Protocols:
• Serial Line Internet Protocol (SLIP)
• Point-to-Point-Protocol (PPP)
• Address Resolution Protocol (ARP)
• Reverse Address Resolution Protocol (RARP)
• Layer 2 Forwarding (L2F)
• Layer 2 Tunneling Protocol (L2TP)
• Point-2-Point Tunneling Protocol (PPTP)
• Integrated Services Digital Network (ISDN)
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7. Q. How the network administrator
detect the problem?
• 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.
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8. Q. What is the difference between
flow control and error control?
• 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.
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9. Q. What is Data Encapsulation ?
• 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.
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10. Q. MAC address works on which layer?
What are the differences of MAC sublayer
and LLC sublayer?
• 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.
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11. Q. What is the difference between half-duplex
and full-duplex?
• In half-duplex, information can flow in both direction but
not simultaneously.
• While in full-duplex, information can flow in both
direction simultaneously.
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12. for watching
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