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CS6250 COMPUTER NETWORKS EXAM 1 2026 GET IT
RIGHT CORRECT ANSWERS EXAM
What are advantages and disadvantages of a layered architecture?
- correct answer- Each protocol layer offers different services. Some
advantages are scalability, flexibility, and ease of adding / removing
components making it easier for cost-effective implementations.
Disadvantages include: 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 and in message headers caused by
abstraction barriers between layers.
What are the differences and similarities of the OSI model and five-
layered Internet model? - correct answer- The OSI model and the
5layered Internet Model have many of the same layers, with the
difference being three of the layers are combined in the 5-layered
model. Specifically the five-layer model combines the application,
presentation, and session layers from the OSI model into a single
application layer.
,What are sockets? - correct 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.https://en.wikipedia.org/wiki/Network_soc ket."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. - correct answer-
Application layer: Service, Interface, Protocol. Ex: Turn
on your smartphone and look at the list of apps. (HTTP,
SMTP, FTP, DNS)
Presentation layer: 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.
Session layer: Responsible for the mechanism that
manages the different transport streams that belong to
,the same session between enduser and application
process. Ex:
teleconference app, it is responsible for tying together
audio and video streaming.
Transport layer: Responsible for the end-toend
communication between end hosts. 2 transport
protocols, TCP and UDP. TCP includes a connection-
oriented service to the applications that are running on
the layer above, guaranteed delivery of the
applicationlayer messages, flow control, and
congestion control mechanism. UDP provides a
connectionless, best-effort service to the applications
that are running in the layer above without reliability,
flow, or congestion control. In this layer the packet is
called a segment.
Network layer: This layer is responsible for moving the
packet of information, called a datagram, from one
host to another. The network layer is responsible for
delivering the datagram to the Transport layer on the
destination host. In this layer there are the IP Protocol
and the routing tables.
Data Link layer: Packets are referred to as frames.
Examples include: ethernet, ppp, wifi. Responsible for
moving the frames from one node (host or router) to
the next node.
Services offered by the data link layer protocol include
reliable delivery (transmission of the data from one
transmitting node, across one link, to the receiving
node.
, Physical layer: This layer is the actual hardware
responsible to transfer bits within a frame between two
nodes c
Provide examples of popular protocols at each layer
of the five-layered Internet model. - correct answer-
Application: NFS, DNS, SNMP, ftp, rcp, telnet, HTTP
Transport: TCP, UDP
Internet: IP, ARP, ICMP
Data Link: PPP, IEEE 802.2, Ethernet Physical
Network: Token Ring, RS-232
What is encapsulation, and how is it used in a layered
model? - correct answer- Encapsulation is when data
(called a header) is appended to the packet through
each layer to signify its on the correct path to the
destination host.
What is the end-to-end (e2e) principle? - correct
answer- A design choice that shaped the current
internet architecture. It states the network core should
be simple and minimal, while the end systems should
carry the intelligence. Network functions should be
simple and essential commonly used functions so any
host can utilize the service and higher form functions
should be built into the application itself. Lower level
layers should be independent and free to perform only
1 | Page
CS6250 COMPUTER NETWORKS EXAM 1 2026 GET IT
RIGHT CORRECT ANSWERS EXAM
What are advantages and disadvantages of a layered architecture?
- correct answer- Each protocol layer offers different services. Some
advantages are scalability, flexibility, and ease of adding / removing
components making it easier for cost-effective implementations.
Disadvantages include: 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 and in message headers caused by
abstraction barriers between layers.
What are the differences and similarities of the OSI model and five-
layered Internet model? - correct answer- The OSI model and the
5layered Internet Model have many of the same layers, with the
difference being three of the layers are combined in the 5-layered
model. Specifically the five-layer model combines the application,
presentation, and session layers from the OSI model into a single
application layer.
,What are sockets? - correct 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.https://en.wikipedia.org/wiki/Network_soc ket."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. - correct answer-
Application layer: Service, Interface, Protocol. Ex: Turn
on your smartphone and look at the list of apps. (HTTP,
SMTP, FTP, DNS)
Presentation layer: 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.
Session layer: Responsible for the mechanism that
manages the different transport streams that belong to
,the same session between enduser and application
process. Ex:
teleconference app, it is responsible for tying together
audio and video streaming.
Transport layer: Responsible for the end-toend
communication between end hosts. 2 transport
protocols, TCP and UDP. TCP includes a connection-
oriented service to the applications that are running on
the layer above, guaranteed delivery of the
applicationlayer messages, flow control, and
congestion control mechanism. UDP provides a
connectionless, best-effort service to the applications
that are running in the layer above without reliability,
flow, or congestion control. In this layer the packet is
called a segment.
Network layer: This layer is responsible for moving the
packet of information, called a datagram, from one
host to another. The network layer is responsible for
delivering the datagram to the Transport layer on the
destination host. In this layer there are the IP Protocol
and the routing tables.
Data Link layer: Packets are referred to as frames.
Examples include: ethernet, ppp, wifi. Responsible for
moving the frames from one node (host or router) to
the next node.
Services offered by the data link layer protocol include
reliable delivery (transmission of the data from one
transmitting node, across one link, to the receiving
node.
, Physical layer: This layer is the actual hardware
responsible to transfer bits within a frame between two
nodes c
Provide examples of popular protocols at each layer
of the five-layered Internet model. - correct answer-
Application: NFS, DNS, SNMP, ftp, rcp, telnet, HTTP
Transport: TCP, UDP
Internet: IP, ARP, ICMP
Data Link: PPP, IEEE 802.2, Ethernet Physical
Network: Token Ring, RS-232
What is encapsulation, and how is it used in a layered
model? - correct answer- Encapsulation is when data
(called a header) is appended to the packet through
each layer to signify its on the correct path to the
destination host.
What is the end-to-end (e2e) principle? - correct
answer- A design choice that shaped the current
internet architecture. It states the network core should
be simple and minimal, while the end systems should
carry the intelligence. Network functions should be
simple and essential commonly used functions so any
host can utilize the service and higher form functions
should be built into the application itself. Lower level
layers should be independent and free to perform only
