A company has enabled ICE to optimize call flows and improve video quality between their Cisco Collaboration endpoints internally and externally. For which reason would you see activity on the TURN…

Question

Options

• AThe video call is using encryption, which is not supported by ICE with CUCM 12.5
• BICE cannot reduce the packet loss on the link
• CA STUN cannot punch holes in the firewall
• DThe video call is using 4K resolution, which is not supported by ICE with CUCM 12.5

• A
  5% (2)
• B
  2% (1)
• C
  91% (39)
• D
  2% (1)

Explanation

ICE (Interactive Connectivity Establishment) uses STUN to allow endpoints to discover their public IP addresses and attempt direct peer-to-peer media connections. However, STUN works via hole-punching, which fails when both endpoints are behind symmetric NATs or strict firewalls that block unsolicited inbound UDP. In those cases, STUN cannot punch holes through the firewall, and the call falls back to using a TURN server, which relays media between the endpoints. This is why TURN server activity appears for external-to-external calls even with ICE enabled. Options A and D are incorrect - ICE/CUCM 12.5 limitations around video encryption or 4K are not real constraints that would force TURN use. Option B is incorrect - TURN does not compensate for packet loss.

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