300-820: Implementing Cisco Collaboration Hybrid and Cloud Technologies

Answer: A, D In a Mobile and Remote Access (MRA) deployment, Expressway-C (Core) sits on the internal network and can use a certificate signed by an internal/private CA because it is never contacted directly by external endpoints. Expressway-E (Edge) is the internet-facing traversal server that external Jabber clients and MRA-registered devices must trust without any additional client-side configuration, so its certificate is required to be signed by a public CA already present in client trust stores.

Answer: D The Expressway-E UC traversal zone validates the traversal client certificate presented by Expressway-C. For an Expressway-C cluster, the configured TLS verification subject name must be the Expressway-C cluster name, included in the SAN of each Expressway-C certificate. **Learn more:** [Cisco Expressway X15.2 MRA Configuration Guide](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/expressway/config_guide/X15-2/mra/exwy_b_mra-deployment-guide-x152/exwy_m_basic-configuration.html)

Answer: D In a hybrid cloud-based deployment that uses Cisco Webex Messenger Service, conferencing is provided by Cisco Webex Meetings Center, which supplies hosted meeting capabilities. Cisco Unified Communications Manager provides the on-premises audio and video calling functions rather than meeting capabilities. **Learn more:** [Cisco Jabber 12.7 Planning Guide — Deployment Scenarios](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/jabber/12_7/cjab_b_planning-guide-cisco-jabber-127/cjab_m_deployment-scenarios-127.html)