A Cisco UCM traversal zone connection fails between Cisco Expressway-C and Expressway-E. Configuration of the zones on both Expressway servers is verified as successful. What are two causes of the…

Question

Options

• AExpressway-C is missing the certification authority certificate of Expressway-E.
• BExpressway-E is missing the certification authority certificate of Expressway-C.
• CThe Expressway servers are missing mutual Mobile and Remote Access certificates.
• DThe call manager certificate must be uploaded to Expressway-C.
• EA DNS SRV record of _collab-edge._tls fails to resolve to the correct domain.

• A
  71% (17)
• C
  4% (1)
• D
  8% (2)
• E
  17% (4)

Explanation

The traversal zone between Expressway-C and Expressway-E uses mutual TLS (mTLS) for authentication, meaning both sides must present and verify each other's certificates. For this to succeed, each Expressway must have the Certificate Authority (CA) certificate that signed the other's server certificate in its trusted CA store. A is correct: if Expressway-C is missing the CA certificate of Expressway-E, it cannot verify Expressway-E's identity and will reject the TLS connection. B is correct: similarly, if Expressway-E is missing the CA certificate of Expressway-C, it cannot verify Expressway-C's identity. Both failures result in a TLS handshake failure independent of zone configuration. Option C is incorrect because MRA certificates are a separate concept. Option D is incorrect because the Call Manager certificate is uploaded to Expressway-C for UCM TLS verification, not for the Expressway-C to Expressway-E traversal zone. Option E describes a DNS lookup failure relevant to external client discovery, not the inter-Expressway zone connection.

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