CS 6250 EXAM 2 ACTUAL EXAM 2026 | COMPUTER
NETWORKS EXAM | ALL QUESTIONS AND CORRECT
ANSWERS | VERIFIED ANSWERS | BRAND NEW
VERSION!
What is the relationship between forwarding and routing? ---------
CORRECT ANSWER-----------------· Forwarding is what a router does when
it receives a packet at its input link, it must determine which output link
that packet should be sent through
§ Forwarding is a function of the data plane and is implemented in the
hardware itself
· Routing involves determining the path form the sender to the receiver
across the network
§ Routing is a function of the control plane and is implemented in the
software
What is the difference between a traditional and SDN approach in
terms of coupling of control and data plane? ---------CORRECT ANSWER-
----------------· Traditional approach - the routing algorithms (control
plane) and forwarding function (data plane) are closely coupled
§ The router runs and participates in the routing algorithms and thus
able to construct the forwarding table
· SDN approach - there is a remote controller that computes and
distributes the forwarding tables to be used for very router
,§ The routers are solely responsible for forwarding, and the remote
controllers are solely responsible for computing and distributing the
forwarding tables
What are the main components of an SDN network and their
responsibilities? ---------CORRECT ANSWER-----------------· SDN-controlled
network elements (switches) - sometimes called the infrastructure
layer, is responsible for the forwarding of traffic in a network based on
the rules computed by the SDN control plane
· SDN controller - a logically centralized entity that acts as an interface
between the network elements and the network-control applications
· Network-control applications - programs that manage the underlying
network by collecting information about the network elements with the
help of the SDN controller
What are the four defining features of an SDN architecture? ---------
CORRECT ANSWER-----------------· 1. Flow-based forwarding - the rules
for forwarding packets in the SDN-controlled switches can be computed
based on any number of header field values in various layers such as
the transport layer, network layer, and data link layer
· 2. Separation of data plane and control plane - the SDN-controlled
switches operate on the data plane, and they only execute the rules in
the flow tables; those rules are computed, installed, and managed by
software that runs on separate servers
,· 3. Network control functions - the SDN control plane (running on
multiple servers for increased performance and availability), consists of
two components: the controller and the network applications
§ The controller maintains up-to-date network state information about
the network devices and elements and provides it to the network-
control applications
· 4. A programmable network - the network-control applications act as
the "brain" of the SDN control plane by managing the network; for
example, applications can include network management, traffic
engineering, security, automation, analytics, etc.
What are the three layers of SDN controllers? ---------CORRECT
ANSWER-----------------· Communication Layer - consists of a protocol
through which the SDN controller and the network controlled elements
communicate; using this protocol the devices send locally observed
events to the SDN controller providing the controller with a current
view of the network state (communication between the SDN controller
and the controlled devices is known as the "southbound" interface)
· Network-wide state-management layer - is about the network-state
that is maintained by the controller; the network-state includes any
information about the state of the hosts, links, switches, and other
controlled elements in the network; network-state information is
needed by the SDN control plane to configure the flow tables
· Interface to the network-control application layer - also known as the
controller's "northbound" interface which the SDN controller interacts
with network-control applications; network-control applications can
read/write network state and flow tables in controller's state-
, management layer; the SDN controller can notify applications of
changes in the network state, based on the event notifications sent by
the SDN-controlled devices
Describe the three perspectives of the SDN landscape. ---------CORRECT
ANSWER-----------------o (a) A plane-oriented view, (b) the SDN layers,
and (c) a system design perspective
What are the SDN layers, going from the data plane up to the
management plane? ---------CORRECT ANSWER-----------------o Network
Infrastructure
o Southbound Interface
o Network Hypervisor/Virtualization
o Network Operating System
o Northbound Interface
o Language-Based Virtualization
o Network Programming Languages
o Network Applications
Describe the responsibility of each layer in the SDN layer perspective -
Infrastructure ---------CORRECT ANSWER-----------------§ Consist of
NETWORKS EXAM | ALL QUESTIONS AND CORRECT
ANSWERS | VERIFIED ANSWERS | BRAND NEW
VERSION!
What is the relationship between forwarding and routing? ---------
CORRECT ANSWER-----------------· Forwarding is what a router does when
it receives a packet at its input link, it must determine which output link
that packet should be sent through
§ Forwarding is a function of the data plane and is implemented in the
hardware itself
· Routing involves determining the path form the sender to the receiver
across the network
§ Routing is a function of the control plane and is implemented in the
software
What is the difference between a traditional and SDN approach in
terms of coupling of control and data plane? ---------CORRECT ANSWER-
----------------· Traditional approach - the routing algorithms (control
plane) and forwarding function (data plane) are closely coupled
§ The router runs and participates in the routing algorithms and thus
able to construct the forwarding table
· SDN approach - there is a remote controller that computes and
distributes the forwarding tables to be used for very router
,§ The routers are solely responsible for forwarding, and the remote
controllers are solely responsible for computing and distributing the
forwarding tables
What are the main components of an SDN network and their
responsibilities? ---------CORRECT ANSWER-----------------· SDN-controlled
network elements (switches) - sometimes called the infrastructure
layer, is responsible for the forwarding of traffic in a network based on
the rules computed by the SDN control plane
· SDN controller - a logically centralized entity that acts as an interface
between the network elements and the network-control applications
· Network-control applications - programs that manage the underlying
network by collecting information about the network elements with the
help of the SDN controller
What are the four defining features of an SDN architecture? ---------
CORRECT ANSWER-----------------· 1. Flow-based forwarding - the rules
for forwarding packets in the SDN-controlled switches can be computed
based on any number of header field values in various layers such as
the transport layer, network layer, and data link layer
· 2. Separation of data plane and control plane - the SDN-controlled
switches operate on the data plane, and they only execute the rules in
the flow tables; those rules are computed, installed, and managed by
software that runs on separate servers
,· 3. Network control functions - the SDN control plane (running on
multiple servers for increased performance and availability), consists of
two components: the controller and the network applications
§ The controller maintains up-to-date network state information about
the network devices and elements and provides it to the network-
control applications
· 4. A programmable network - the network-control applications act as
the "brain" of the SDN control plane by managing the network; for
example, applications can include network management, traffic
engineering, security, automation, analytics, etc.
What are the three layers of SDN controllers? ---------CORRECT
ANSWER-----------------· Communication Layer - consists of a protocol
through which the SDN controller and the network controlled elements
communicate; using this protocol the devices send locally observed
events to the SDN controller providing the controller with a current
view of the network state (communication between the SDN controller
and the controlled devices is known as the "southbound" interface)
· Network-wide state-management layer - is about the network-state
that is maintained by the controller; the network-state includes any
information about the state of the hosts, links, switches, and other
controlled elements in the network; network-state information is
needed by the SDN control plane to configure the flow tables
· Interface to the network-control application layer - also known as the
controller's "northbound" interface which the SDN controller interacts
with network-control applications; network-control applications can
read/write network state and flow tables in controller's state-
, management layer; the SDN controller can notify applications of
changes in the network state, based on the event notifications sent by
the SDN-controlled devices
Describe the three perspectives of the SDN landscape. ---------CORRECT
ANSWER-----------------o (a) A plane-oriented view, (b) the SDN layers,
and (c) a system design perspective
What are the SDN layers, going from the data plane up to the
management plane? ---------CORRECT ANSWER-----------------o Network
Infrastructure
o Southbound Interface
o Network Hypervisor/Virtualization
o Network Operating System
o Northbound Interface
o Language-Based Virtualization
o Network Programming Languages
o Network Applications
Describe the responsibility of each layer in the SDN layer perspective -
Infrastructure ---------CORRECT ANSWER-----------------§ Consist of
