Computer Networks CS 6250 Actual Exam Questions
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- 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. Dis-
advantages include: some layers func-
What are advantages and disadvan-
tionality depends on the information from
tages of a layered architecture?
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.
- ANSWER The OSI model and the 5-lay-
ered Internet Model have many of the
same layers, with the difference being
What are the differences and similarities
three of the layers are combined in the
of the OSI model and five-layered Inter-
5-layered model. Specifically the five-lay-
net model?
er model combines the application, pre-
sentation, and session layers from the
OSI model into a single application layer.
- 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
What are sockets? are created only during the lifetime of a
process of an application running in the
node.https://en.wikipedia.org/wiki/Net-
work_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
, Computer Networks CS 6250 Actual Exam Questions
With Reviewed 100% Correct Detailed Answers
Guaranteed Pass!!
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
- ANSWER Application layer: Service, In-
terface, Protocol. Ex: Turn on your smart-
phone and look at the list of apps. (HTTP,
SMTP, FTP, DNS)
Presentation layer: Plays intermediate
role of formatting the information re-
ceived from the layer below and deliver-
ing it to the application layer. Ex: convert-
ing big endian to little endian.
Session layer: Responsible for the mech-
anism that manages the different trans-
port streams that belong to the same
session between end-user and applica-
tion process. Ex: teleconference app, it is
responsible for tying together audio and
video streaming.
Transport layer: Responsible for the
Describe each layer of the OSI model.
end-to-end communication between end
hosts. 2 transport protocols, TCP and
UDP. TCP includes a connection-orient-
ed service to the applications that are
running on the layer above, guaranteed
delivery of the application-layer mes-
sages, flow control, and congestion con-
trol mechanism. UDP provides a con-
nectionless, best-effort service to the ap-
plications that are running in the layer
above without reliability, flow, or conges-
tion control. In this layer the packet is
called a segment.
Network layer: This layer is responsi-
ble for moving the packet of information,
called a datagram, from one host to an-
other. The network layer is responsible
, Computer Networks CS 6250 Actual Exam Questions
With Reviewed 100% Correct Detailed Answers
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for delivering the datagram to the Trans-
port 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 actu-
al hardware responsible to transfer bits
within a frame between t
- ANSWER Application: NFS, DNS,
SNMP, ftp, rcp, telnet, HTTP
Provide examples of popular protocols
Transport: TCP, UDP
at each layer of the five-layered Internet Internet: IP, ARP, ICMP
model.
Data Link: PPP, IEEE 802.2, Ethernet
Physical Network: Token Ring, RS-232
- ANSWER Encapsulation is when data
What is encapsulation, and how is it used (called a header) is appended to the
in a layered model? packet through each layer to signify its on
the correct path to the destination host.
- 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 common-
What is the end-to-end (e2e) principle?
ly used functions so any host can uti-
lize the service and higher form functions
should be built into the application itself.
Lower level layers should be indepen-
dent and free to perform only their de-
signed function and the higher-level lay-
, Computer Networks CS 6250 Actual Exam Questions
With Reviewed 100% Correct Detailed Answers
Guaranteed Pass!!
ers deal with the more intricate functions
that deal with the specific application.
- ANSWER Violations include firewalls
and traffic filters. Firewalls violate be-
cause they are intermediate devices that
are operated between two end hosts and
they can drop the end host communica-
tions. Network Address Translation (NAT)
What are the examples of a violation of boxes are also a violation because it
e2e principle? uses the single public IP address and
distributes a new IP scheme to the hosts
connected to it to route data through
re-writing the header info to route to the
correct destination host. NAT boxes are
a violation because they are not globally
addressable or routable.
- ANSWER An hourglass shaped model
of the Internet where the outer bands
What is the EvoArch model? are more frequently modified or replaced
and the further in you go the harder it is
for that layer to be altered or modified.
- ANSWER EvoArch is a discrete-time
model that is executed over rounds. At
each round, we perform the following
steps: A) We introduce new nodes, and
we place them randomly at layers. B)
We examine all layers, from the top to
the bottom, and we perform the following
tasks: 1) We connect the new nodes that
Explain a round in the EvoArch model. we may have just introduced to that lay-
er, by choosing substrates based on the
generality probabilities of the layer below
s(l 1), and by choosing products for them
based on the generality probability of the
current layer s(l). 2) We update the value
of each node at each layer l, given that
we may have new nodes added to the
same layer l. 3) We examine all nodes,
With Reviewed 100% Correct Detailed Answers
Guaranteed Pass!!
- 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. Dis-
advantages include: some layers func-
What are advantages and disadvan-
tionality depends on the information from
tages of a layered architecture?
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.
- ANSWER The OSI model and the 5-lay-
ered Internet Model have many of the
same layers, with the difference being
What are the differences and similarities
three of the layers are combined in the
of the OSI model and five-layered Inter-
5-layered model. Specifically the five-lay-
net model?
er model combines the application, pre-
sentation, and session layers from the
OSI model into a single application layer.
- 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
What are sockets? are created only during the lifetime of a
process of an application running in the
node.https://en.wikipedia.org/wiki/Net-
work_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
, Computer Networks CS 6250 Actual Exam Questions
With Reviewed 100% Correct Detailed Answers
Guaranteed Pass!!
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
- ANSWER Application layer: Service, In-
terface, Protocol. Ex: Turn on your smart-
phone and look at the list of apps. (HTTP,
SMTP, FTP, DNS)
Presentation layer: Plays intermediate
role of formatting the information re-
ceived from the layer below and deliver-
ing it to the application layer. Ex: convert-
ing big endian to little endian.
Session layer: Responsible for the mech-
anism that manages the different trans-
port streams that belong to the same
session between end-user and applica-
tion process. Ex: teleconference app, it is
responsible for tying together audio and
video streaming.
Transport layer: Responsible for the
Describe each layer of the OSI model.
end-to-end communication between end
hosts. 2 transport protocols, TCP and
UDP. TCP includes a connection-orient-
ed service to the applications that are
running on the layer above, guaranteed
delivery of the application-layer mes-
sages, flow control, and congestion con-
trol mechanism. UDP provides a con-
nectionless, best-effort service to the ap-
plications that are running in the layer
above without reliability, flow, or conges-
tion control. In this layer the packet is
called a segment.
Network layer: This layer is responsi-
ble for moving the packet of information,
called a datagram, from one host to an-
other. The network layer is responsible
, Computer Networks CS 6250 Actual Exam Questions
With Reviewed 100% Correct Detailed Answers
Guaranteed Pass!!
for delivering the datagram to the Trans-
port 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 actu-
al hardware responsible to transfer bits
within a frame between t
- ANSWER Application: NFS, DNS,
SNMP, ftp, rcp, telnet, HTTP
Provide examples of popular protocols
Transport: TCP, UDP
at each layer of the five-layered Internet Internet: IP, ARP, ICMP
model.
Data Link: PPP, IEEE 802.2, Ethernet
Physical Network: Token Ring, RS-232
- ANSWER Encapsulation is when data
What is encapsulation, and how is it used (called a header) is appended to the
in a layered model? packet through each layer to signify its on
the correct path to the destination host.
- 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 common-
What is the end-to-end (e2e) principle?
ly used functions so any host can uti-
lize the service and higher form functions
should be built into the application itself.
Lower level layers should be indepen-
dent and free to perform only their de-
signed function and the higher-level lay-
, Computer Networks CS 6250 Actual Exam Questions
With Reviewed 100% Correct Detailed Answers
Guaranteed Pass!!
ers deal with the more intricate functions
that deal with the specific application.
- ANSWER Violations include firewalls
and traffic filters. Firewalls violate be-
cause they are intermediate devices that
are operated between two end hosts and
they can drop the end host communica-
tions. Network Address Translation (NAT)
What are the examples of a violation of boxes are also a violation because it
e2e principle? uses the single public IP address and
distributes a new IP scheme to the hosts
connected to it to route data through
re-writing the header info to route to the
correct destination host. NAT boxes are
a violation because they are not globally
addressable or routable.
- ANSWER An hourglass shaped model
of the Internet where the outer bands
What is the EvoArch model? are more frequently modified or replaced
and the further in you go the harder it is
for that layer to be altered or modified.
- ANSWER EvoArch is a discrete-time
model that is executed over rounds. At
each round, we perform the following
steps: A) We introduce new nodes, and
we place them randomly at layers. B)
We examine all layers, from the top to
the bottom, and we perform the following
tasks: 1) We connect the new nodes that
Explain a round in the EvoArch model. we may have just introduced to that lay-
er, by choosing substrates based on the
generality probabilities of the layer below
s(l 1), and by choosing products for them
based on the generality probability of the
current layer s(l). 2) We update the value
of each node at each layer l, given that
we may have new nodes added to the
same layer l. 3) We examine all nodes,
