What is a characteristic of VXLAN?

Question

Options

• AIt extends Layer 2 and Layer 3 overlay networks over a Layer 2 underlay
• BIt has a 12-byte packet header
• CIt uses TCP for transport
• DIts frame encapsulation is performed by MAC-in-UDP

• A
  4% (1)
• B
  4% (1)
• D
  93% (25)

Explanation

VXLAN (Virtual Extensible LAN) encapsulates original Layer 2 Ethernet frames within UDP packets, specifically using a MAC-in-UDP encapsulation method - this is its defining characteristic and why D is correct. Option A is incorrect because VXLAN extends Layer 2 overlay networks over a Layer 3 underlay (not Layer 2), which is actually its primary purpose for stretching VLANs across routed networks. Option B is wrong because VXLAN uses an 8-byte header (not 12 bytes), which includes a 24-bit VNI (VXLAN Network Identifier) allowing over 16 million segments. Option C is incorrect because VXLAN uses UDP (port 4789) for transport, not TCP - UDP was chosen for its lower overhead and better scalability in data center environments.

Memory Tip: Think of the acronym order - VXLAN = Virtual eXtensible LAN, and it works by wrapping (encapsulating) your LAN frames in UDP, just like putting a letter (MAC frame) inside an envelope (UDP packet) - "MAC stuffed in UDP" = MAC-in-UDP.

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