CS6250 COMPUTER NETWORKS EXAM 1 2025
UPDATE/PRACTICE QUESTIONS AND CORRECT VERIFIED
ANSWERS (complete solutions)ASSURED SUCCESS/GRADED
A+!!!
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_socket."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 end-user and
application process. Ex: teleconference app, it is responsible for tying together
audio and video streaming.
Transport layer: Responsible for the end-to-end 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 application-layer 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 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 5-layered 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 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 their designed function and the higher-level layers deal with the more
intricate functions that deal with the specific application.
UPDATE/PRACTICE QUESTIONS AND CORRECT VERIFIED
ANSWERS (complete solutions)ASSURED SUCCESS/GRADED
A+!!!
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_socket."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 end-user and
application process. Ex: teleconference app, it is responsible for tying together
audio and video streaming.
Transport layer: Responsible for the end-to-end 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 application-layer 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 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 5-layered 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 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 their designed function and the higher-level layers deal with the more
intricate functions that deal with the specific application.
