NE NE Network Virtualization 1 — Questions and Answers
Question 1: What does SDN (Software-Defined Networking) fundamentally separate within a network architecture?
- Data plane from the physical hardware
- Control plane from the data plane (Correct answer)
- Management plane from the control plane
- Application plane from the management plane
Correct answer: Control plane from the data plane
SDN separates the control plane (decision-making logic) from the data plane (packet forwarding), enabling centralized, programmable network management.
Question 2: Which protocol is most commonly used as the southbound API in SDN for communication between an SDN controller and network forwarding devices?
- OSPF
- BGP
- OpenFlow (Correct answer)
- SNMP
Correct answer: OpenFlow
OpenFlow is the primary southbound API protocol that allows SDN controllers to program the forwarding tables of network devices.
Question 3: What is the primary purpose of VXLAN (Virtual Extensible LAN)?
- To replace VLANs entirely in small networks
- To extend Layer 2 networks over a Layer 3 infrastructure (Correct answer)
- To provide encryption for wireless networks
- To manage IP address allocation across data centers
Correct answer: To extend Layer 2 networks over a Layer 3 infrastructure
VXLAN encapsulates Layer 2 Ethernet frames in UDP packets, allowing Layer 2 network segments to span a Layer 3 routed infrastructure.
Question 4: What is the IANA-assigned standard UDP destination port used by VXLAN?
- 4789 (Correct answer)
- 8472
- 4500
- 6635
Correct answer: 4789
IANA assigned UDP port 4789 as the standard VXLAN destination port, though some early implementations used 8472.
Question 5: What does NFV (Network Functions Virtualization) primarily aim to achieve?
- Replace physical switches with software-only virtual switches
- Run network functions as software on commodity hardware (Correct answer)
- Virtualize IP address management across clouds
- Create encrypted tunnels between data center locations
Correct answer: Run network functions as software on commodity hardware
NFV enables network functions such as firewalls, load balancers, and routers to run as software (VNFs) on standard commodity servers instead of dedicated proprietary appliances.
Question 6: What is the maximum number of unique VLAN IDs supported by the IEEE 802.1Q standard?
- 256
- 1024
- 4094 (Correct answer)
- 16,777,214
Correct answer: 4094
IEEE 802.1Q uses a 12-bit VLAN ID field, supporting VLANs 1–4094 (4,096 total values, with 0 and 4095 reserved).
Question 7: What is a key advantage of using overlay networks in a network virtualization architecture?
- They eliminate the need for physical switches entirely
- They provide logical network isolation independent of the physical topology (Correct answer)
- They automatically reduce IP address consumption
- They automatically assign VLANs to end devices
Correct answer: They provide logical network isolation independent of the physical topology
Overlay networks create logical topologies on top of the physical underlay, providing isolation and flexibility without requiring changes to the underlying physical infrastructure.
NE NE Network Virtualization 1
What does SDN (Software-Defined Networking) fundamentally separate within a network architecture?