WGU D415 SOFTWARE DEFINED
NETWORKING PA AND OA ACTUAL EXAM
2026 EXPLORE NEW 161 QUESTIONS WITH
ANSWERS GRADED A+
⩥ Active Networks. Answer: Programmability in Networks
⩥ Switchlets. Answer: Network virtualization (VINI)
⩥ Why Separate Control?. Answer: 1. Rapid Innovation. Control logic
not tied to hardware
2. Network Wide View. Easier to infer network behavior
3. More flexibility. Can add service more easily
⩥ verify Mininet install. Answer: 1. cd /Users/litinsky/Coursera-SDN
2. vagrant up
3. vagrant ssh
4. cd mininet
5. sudo mn --test pingall -topo single,3
6. sudo python ex3.py
,⩥ Mininet command line options. Answer: --topo defines topology via
command line options on startup
--switch defines the switch to be used (default is OVSK switch)
--controller defines the controller to be used
⩥ run a custom topology. Answer: sudo mn --custom
~/mininet/custom/topo-2sw-2host.py --topo mytopo --test pingall
⩥ Mininet Readme. Answer:
https://github.com/PrincetonUniversity/Coursera-
SDN/blob/master/assignments/mininet-topology/README.md
⩥ run mininet script. Answer: 1. cd /Users/litinsky/Coursera-SDN
2. vagrant up
3. vagrant ssh
4. cd mininet
5. sudo python ex3.py
⩥ mininet.cli.CLI(net). Answer: adding before net.stop() will escape to
interactive CLI
⩥ addLink. Answer: allows to specify to Bandwidth (bw) in Mbps,
Delay (delay) , maximum queue size (max_queue_size), Loss (loss) as a
percentage
,⩥ what is control/data separation?. Answer: control plane controls
forwarding behavior in a network
data plane forward traffic according to control plane logic
⩥ why is control/data separation a good idea?. Answer: 1. Independent
evolution and development (software control of the network can evolve
independently from hardware)
2. Allows control from a high-level network program (easier debug and
control)
⩥ what are opportunities and challenges for SDN. Answer:
Opportunities:
1. Data Centers - VM Migration, Layer 2 routing
2. Routing - More control over decision logic
3. Enterprise Networks - security applications
4. Research networks (coexist with production networks)
⩥ control plane. Answer: controls forwarding behavior in a network
Example: routing protocols, network middlebox
⩥ data plane. Answer: forward traffic according to control plane logic
Example: IP Forwarding, Layer 2 switching
, ⩥ example: Yahoo Datacenter. Answer: 20,000 servers/cluster = 400,000
VMs
⩥ DOS attacke. Answer: Denial of Service Attack
Filtering
1. Measurement system detects attack
2. Identify entry point and victim of attack
3. Drop offending traffic at the entry point
⩥ AT&T IRSCP (commercial version of RCP)
1. Insert null route for particular flows. Answer:
⩥ SDN challenges. Answer: 1. Scalability (control plane is responsible
for many forwarding elements)
2. Reliability (what happens when a controller fails)?
⩥ Interdomain routing. Answer: Today's Border Gateway Protocol
(BGP) artificially constraints routes:
1. route selection is based on a fixed set of steps
2. limited knows to inbound/outbound traffic
3. very difficult to incorporate new info (time of day)
NETWORKING PA AND OA ACTUAL EXAM
2026 EXPLORE NEW 161 QUESTIONS WITH
ANSWERS GRADED A+
⩥ Active Networks. Answer: Programmability in Networks
⩥ Switchlets. Answer: Network virtualization (VINI)
⩥ Why Separate Control?. Answer: 1. Rapid Innovation. Control logic
not tied to hardware
2. Network Wide View. Easier to infer network behavior
3. More flexibility. Can add service more easily
⩥ verify Mininet install. Answer: 1. cd /Users/litinsky/Coursera-SDN
2. vagrant up
3. vagrant ssh
4. cd mininet
5. sudo mn --test pingall -topo single,3
6. sudo python ex3.py
,⩥ Mininet command line options. Answer: --topo defines topology via
command line options on startup
--switch defines the switch to be used (default is OVSK switch)
--controller defines the controller to be used
⩥ run a custom topology. Answer: sudo mn --custom
~/mininet/custom/topo-2sw-2host.py --topo mytopo --test pingall
⩥ Mininet Readme. Answer:
https://github.com/PrincetonUniversity/Coursera-
SDN/blob/master/assignments/mininet-topology/README.md
⩥ run mininet script. Answer: 1. cd /Users/litinsky/Coursera-SDN
2. vagrant up
3. vagrant ssh
4. cd mininet
5. sudo python ex3.py
⩥ mininet.cli.CLI(net). Answer: adding before net.stop() will escape to
interactive CLI
⩥ addLink. Answer: allows to specify to Bandwidth (bw) in Mbps,
Delay (delay) , maximum queue size (max_queue_size), Loss (loss) as a
percentage
,⩥ what is control/data separation?. Answer: control plane controls
forwarding behavior in a network
data plane forward traffic according to control plane logic
⩥ why is control/data separation a good idea?. Answer: 1. Independent
evolution and development (software control of the network can evolve
independently from hardware)
2. Allows control from a high-level network program (easier debug and
control)
⩥ what are opportunities and challenges for SDN. Answer:
Opportunities:
1. Data Centers - VM Migration, Layer 2 routing
2. Routing - More control over decision logic
3. Enterprise Networks - security applications
4. Research networks (coexist with production networks)
⩥ control plane. Answer: controls forwarding behavior in a network
Example: routing protocols, network middlebox
⩥ data plane. Answer: forward traffic according to control plane logic
Example: IP Forwarding, Layer 2 switching
, ⩥ example: Yahoo Datacenter. Answer: 20,000 servers/cluster = 400,000
VMs
⩥ DOS attacke. Answer: Denial of Service Attack
Filtering
1. Measurement system detects attack
2. Identify entry point and victim of attack
3. Drop offending traffic at the entry point
⩥ AT&T IRSCP (commercial version of RCP)
1. Insert null route for particular flows. Answer:
⩥ SDN challenges. Answer: 1. Scalability (control plane is responsible
for many forwarding elements)
2. Reliability (what happens when a controller fails)?
⩥ Interdomain routing. Answer: Today's Border Gateway Protocol
(BGP) artificially constraints routes:
1. route selection is based on a fixed set of steps
2. limited knows to inbound/outbound traffic
3. very difficult to incorporate new info (time of day)
