WGU D415 SOFTWARE DEFINED
NETWORKING PA AND OA SCRIPT 2026
TESTED QUESTIONS WITH COMPLETE
SOLUTIONS GRADED A+
⩥ Control Plane. Answer: The part of the network responsible for
making decisions about where traffic is sent (routing decisions and
network intelligence).
⩥ Data Plane. Answer: The part of the network responsible for
forwarding traffic based on instructions from the control plane. Also
called the forwarding plane.
⩥ Management Plane. Answer: The layer responsible for monitoring,
configuring, and managing network devices, often using protocols like
SNMP or NETCONF.
⩥ SDN Controller. Answer: A centralized software application that
manages the control plane, communicates with network devices, and
provides a unified view of the network.
⩥ Northbound API. Answer: An interface between the SDN controller
and applications/business logic, allowing applications to request network
services (e.g., REST APIs).
,⩥ Southbound API. Answer: An interface between the SDN controller
and network devices (data plane), used to push forwarding rules (e.g.,
OpenFlow, NETCONF).
⩥ East-West API. Answer: An interface used for communication
between multiple SDN controllers to ensure consistency and
coordination in distributed environments.
⩥ OpenFlow. Answer: A southbound protocol that allows the SDN
controller to communicate with and program the forwarding tables of
network switches and routers.
⩥ Flow Table. Answer: A table inside an OpenFlow-enabled switch that
stores rules (flow entries) used to match and forward incoming packets.
⩥ Flow Entry. Answer: A rule in a flow table consisting of match fields,
priority, counters, and instructions for handling matching packets.
⩥ Match Fields. Answer: Attributes in a flow entry used to identify
packets (e.g., source/destination IP, MAC address, port number, VLAN
tag).
, ⩥ Action. Answer: The instruction in a flow entry that tells the switch
what to do with a matched packet (e.g., forward, drop, modify, send to
controller).
⩥ Packet-In Message. Answer: An OpenFlow message sent from a
switch to the controller when a packet does not match any flow entry.
⩥ Packet-Out Message. Answer: An OpenFlow message sent from the
controller to a switch instructing it how to handle a specific packet.
⩥ Flow-Mod Message. Answer: An OpenFlow message used by the
controller to add, modify, or delete flow entries in a switch's flow table.
⩥ Proactive Flow Installation. Answer: A method where the SDN
controller pre-installs flow rules in switches before traffic arrives,
reducing latency.
⩥ Reactive Flow Installation. Answer: A method where flow rules are
installed in switches only when unmatched traffic triggers a Packet-In
message to the controller.
⩥ Network Function Virtualization (NFV). Answer: The concept of
replacing dedicated hardware network appliances (firewalls, load
balancers, routers) with software running on standard servers.
NETWORKING PA AND OA SCRIPT 2026
TESTED QUESTIONS WITH COMPLETE
SOLUTIONS GRADED A+
⩥ Control Plane. Answer: The part of the network responsible for
making decisions about where traffic is sent (routing decisions and
network intelligence).
⩥ Data Plane. Answer: The part of the network responsible for
forwarding traffic based on instructions from the control plane. Also
called the forwarding plane.
⩥ Management Plane. Answer: The layer responsible for monitoring,
configuring, and managing network devices, often using protocols like
SNMP or NETCONF.
⩥ SDN Controller. Answer: A centralized software application that
manages the control plane, communicates with network devices, and
provides a unified view of the network.
⩥ Northbound API. Answer: An interface between the SDN controller
and applications/business logic, allowing applications to request network
services (e.g., REST APIs).
,⩥ Southbound API. Answer: An interface between the SDN controller
and network devices (data plane), used to push forwarding rules (e.g.,
OpenFlow, NETCONF).
⩥ East-West API. Answer: An interface used for communication
between multiple SDN controllers to ensure consistency and
coordination in distributed environments.
⩥ OpenFlow. Answer: A southbound protocol that allows the SDN
controller to communicate with and program the forwarding tables of
network switches and routers.
⩥ Flow Table. Answer: A table inside an OpenFlow-enabled switch that
stores rules (flow entries) used to match and forward incoming packets.
⩥ Flow Entry. Answer: A rule in a flow table consisting of match fields,
priority, counters, and instructions for handling matching packets.
⩥ Match Fields. Answer: Attributes in a flow entry used to identify
packets (e.g., source/destination IP, MAC address, port number, VLAN
tag).
, ⩥ Action. Answer: The instruction in a flow entry that tells the switch
what to do with a matched packet (e.g., forward, drop, modify, send to
controller).
⩥ Packet-In Message. Answer: An OpenFlow message sent from a
switch to the controller when a packet does not match any flow entry.
⩥ Packet-Out Message. Answer: An OpenFlow message sent from the
controller to a switch instructing it how to handle a specific packet.
⩥ Flow-Mod Message. Answer: An OpenFlow message used by the
controller to add, modify, or delete flow entries in a switch's flow table.
⩥ Proactive Flow Installation. Answer: A method where the SDN
controller pre-installs flow rules in switches before traffic arrives,
reducing latency.
⩥ Reactive Flow Installation. Answer: A method where flow rules are
installed in switches only when unmatched traffic triggers a Packet-In
message to the controller.
⩥ Network Function Virtualization (NFV). Answer: The concept of
replacing dedicated hardware network appliances (firewalls, load
balancers, routers) with software running on standard servers.
