CS6250 COMPUTER NETWORKS ACTUAL
CERTIFICATION EXAMINATION 2026
COMPREHENSIVE QUESTIONS WITH
CORRECTLY WELL DEFINED ANSWERS
GRADED A+
⩥ Layered Architecture. Answer: Each protocol layer offers different
services.
⩥ Layered Architecture Advantages. Answer: - Scalability,
- Flexibility
- Ease of adding / removing components making it easier for cost-
effective implementations.
⩥ Layered Architecture Disadvantages. Answer: - Some layers
functionality depends on the information from the other layer and
violates the goal of layer separation;
- One layer may duplicate lower layer functionalities
- Overhead both in computation
- Overhead in message headers caused by abstraction barriers between
layers.
,⩥ OSI and Five-Layered Internet model Similarities. Answer: Many of
the layers are the same
⩥ OSI and Five-Layered Internet model Differences. Answer: - Three of
the layers are combined in the 5-layered model.
- Specifically the five-layer model combines the
- Application
- Presentation
- Session layers
from the OSI model into a single Application layer.
⩥ What are sockets?. Answer: - A network socket is a software structure
within a network node of a computer network that serves as an endpoint
for sending and receiving data across the network.
- The structure and properties of a socket are defined by an application
programming interface (API) for the networking architecture.
- Sockets are created only during the lifetime of a process of an
application running in the node.
- ."A process sends messages into, and receives messages from, the
network through a software interface called a socket.
- Let's consider an analogy to help us understand processes and sockets.
A process is analogous to a house and its socket is analogous to its
door....a socket is the interface between the application layer and the
transport layer within a host." - Kurose and Ross, 2.1
,⩥ Describe each layer of the OSI model.. Answer: - Application layer:
Service, Interface, Protocol.
- Presentation layer: Plays intermediate role of formatting the
information received from the layer below and delivering it to the
application layer.
- Session layer: Responsible for the mechanism that manages the
different transport streams that belong to the same session between end-
user and application process.
- Transport layer: Responsible for the end-to-end communication
between end hosts.
Network layer: This layer is responsible for moving the packet of
information, called a datagram, from one host to another.
- Data Link layer: Responsible for moving the frames from one node
(host or router) to the next node.
- Physical layer: This layer is the actual hardware responsible to transfer
bits within a frame between two nodes c
⩥ OSI Model Application Layer. Answer: - Service, Interface, Protocol.
, Ex: Turn on your smartphone and look at the list of apps. (HTTP, SMTP,
FTP, DNS)
⩥ OSI Model Presentation Layer. Answer: - Plays intermediate role of
formatting the information received from the layer below and delivering
it to the application layer.
Ex: converting big endian to little endian.
⩥ OSI Model Session Layer. Answer: - Responsible for the mechanism
that manages the different transport streams that belong to the same
session between end-user and application process.
Ex: teleconference app, it is responsible for tying together audio and
video streaming.
⩥ OSI Model Network Layer. Answer: - This layer is responsible for
moving the packet of information, called a datagram, from one host to
another.
- Responsible for delivering the datagram to the Transport layer on the
destination host.
CERTIFICATION EXAMINATION 2026
COMPREHENSIVE QUESTIONS WITH
CORRECTLY WELL DEFINED ANSWERS
GRADED A+
⩥ Layered Architecture. Answer: Each protocol layer offers different
services.
⩥ Layered Architecture Advantages. Answer: - Scalability,
- Flexibility
- Ease of adding / removing components making it easier for cost-
effective implementations.
⩥ Layered Architecture Disadvantages. Answer: - Some layers
functionality depends on the information from the other layer and
violates the goal of layer separation;
- One layer may duplicate lower layer functionalities
- Overhead both in computation
- Overhead in message headers caused by abstraction barriers between
layers.
,⩥ OSI and Five-Layered Internet model Similarities. Answer: Many of
the layers are the same
⩥ OSI and Five-Layered Internet model Differences. Answer: - Three of
the layers are combined in the 5-layered model.
- Specifically the five-layer model combines the
- Application
- Presentation
- Session layers
from the OSI model into a single Application layer.
⩥ What are sockets?. Answer: - A network socket is a software structure
within a network node of a computer network that serves as an endpoint
for sending and receiving data across the network.
- The structure and properties of a socket are defined by an application
programming interface (API) for the networking architecture.
- Sockets are created only during the lifetime of a process of an
application running in the node.
- ."A process sends messages into, and receives messages from, the
network through a software interface called a socket.
- Let's consider an analogy to help us understand processes and sockets.
A process is analogous to a house and its socket is analogous to its
door....a socket is the interface between the application layer and the
transport layer within a host." - Kurose and Ross, 2.1
,⩥ Describe each layer of the OSI model.. Answer: - Application layer:
Service, Interface, Protocol.
- Presentation layer: Plays intermediate role of formatting the
information received from the layer below and delivering it to the
application layer.
- Session layer: Responsible for the mechanism that manages the
different transport streams that belong to the same session between end-
user and application process.
- Transport layer: Responsible for the end-to-end communication
between end hosts.
Network layer: This layer is responsible for moving the packet of
information, called a datagram, from one host to another.
- Data Link layer: Responsible for moving the frames from one node
(host or router) to the next node.
- Physical layer: This layer is the actual hardware responsible to transfer
bits within a frame between two nodes c
⩥ OSI Model Application Layer. Answer: - Service, Interface, Protocol.
, Ex: Turn on your smartphone and look at the list of apps. (HTTP, SMTP,
FTP, DNS)
⩥ OSI Model Presentation Layer. Answer: - Plays intermediate role of
formatting the information received from the layer below and delivering
it to the application layer.
Ex: converting big endian to little endian.
⩥ OSI Model Session Layer. Answer: - Responsible for the mechanism
that manages the different transport streams that belong to the same
session between end-user and application process.
Ex: teleconference app, it is responsible for tying together audio and
video streaming.
⩥ OSI Model Network Layer. Answer: - This layer is responsible for
moving the packet of information, called a datagram, from one host to
another.
- Responsible for delivering the datagram to the Transport layer on the
destination host.
