300-415 Question #357: Real Exam Question with Answer & Explanation

Question

Options

• AIt prevents SD-WAN Edge routers from forming sessions with public transports among different service providers.
• BIt facilitates SD-WAN Edge routers to stay behind a NAT-enabled firewall while the transport addresses of the SD-WAN controller are unNAT-ed.
• CIt allows WAN Edge routers to form sessions among MPLS TLOCs using only public IP addresses.
• DIt facilitates SD-WAN routers and controllers to discover their own mapped or translated IP addresses and port numbers.

Explanation

The vBond orchestrator acts as a STUN (Session Traversal Utilities for NAT) server, enabling SD-WAN routers and controllers to discover their own public or translated IP addresses and port numbers when behind NAT devices.

Common mistakes.

• A. The STUN server function does not prevent edge routers from forming sessions with public transports; it actually facilitates connectivity by revealing NAT-translated addresses to enable session establishment.
• B. vBond's STUN role is not about keeping edge routers behind a NAT firewall while unNATing controller addresses; it helps devices discover their own translated addresses so they can communicate their reachable TLOC to others.
• C. STUN is not specifically for MPLS TLOCs or restricted to public IP addresses; it is a general NAT traversal utility applicable to any transport where address translation is present.

Concept tested. vBond STUN server role for NAT address discovery

Reference. https://www.cisco.com/c/en/us/td/docs/routers/sdwan/configuration/system-interface/vedge-20-x/systems-interfaces-book/system-interface.html

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