DNS Queries for Jabber Client Connectivity
Question
Company ABC is deploying Mobile and Remote Access (MRA) to allow employees to login Jabber clients from anywhere on the internet.
Which two DNS queries must a Jabber client resolve from outside of the corporate network? (Choose two.)
Answers
Explanations
Click on the arrows to vote for the correct answer
A. B. C. D. E. F. G.BF.
https://www.cisco.com/c/dam/en/us/td/docs/voice_ip_comm/expressway/config_guide/X8-11/Mobile-Remote-Access-via-Expressway-Deployment-Mobile and Remote Access (MRA) is a solution that allows employees to access corporate resources from outside the corporate network securely. Jabber is a popular Cisco Unified Communication application that supports MRA. In this scenario, Company ABC is deploying MRA for Jabber users.
To connect to the corporate network, Jabber clients outside of the corporate network must resolve specific DNS queries to discover the Expressway servers and other services required for MRA. The DNS queries that Jabber clients must resolve are as follows:
DNS A record for the Expressway-E FQDN (Answer E) The Expressway-E is a component of the MRA solution that acts as a traversal server. It allows Jabber clients to communicate with other Unified Communication services inside the corporate network, such as the Cisco Unified Communications Manager (CUCM) and the Cisco Unity Connection (CUC). Jabber clients must resolve the DNS A record for the Expressway-E Fully Qualified Domain Name (FQDN) to discover its IP address and establish a connection.
DNS SRV record for_collab-edge._tls.abc.com (Answer B) Collab-Edge is a service on the Expressway-E that provides secure access to Unified Communication services inside the corporate network. Jabber clients must resolve the DNS SRV record for_collab-edge._tls.abc.com to discover the hostname and port number of the Collab-Edge service.
Therefore, the correct answers are B and E.
The other answer options are not required for Jabber clients to connect to the corporate network via MRA. Here is a brief explanation of why:
A. DNS A record for_cisco-uds._tls.abc.com: This DNS query is not required for MRA, but it is used by Jabber clients to locate the Cisco Unified Communications Manager (CUCM) server for user authentication and directory services when they are inside the corporate network.
C. DNS A record for _collab-edge_tls.abc.com: This DNS query is not required because there is no underscore character before the protocol type.
D. DNS SRV record for _cuplogin._tcp.abc.com: This DNS query is not required for MRA, but it is used by Jabber clients to locate the Cisco Unified Presence (CUP) server for instant messaging and presence services when they are inside the corporate network.
F. DNS SRV record for_cisco-uds._tcp.abc.com: This DNS query is not required for MRA, but it is used by Jabber clients to locate the Cisco Unified Communications Manager (CUCM) server for user authentication and directory services when they are inside the corporate network.
G. DNS SRV record for_cuplogin._tls.abc.com: This DNS query is not required for MRA, but it is used by Jabber clients to locate the Cisco Unified Presence (CUP) server for instant messaging and presence services when they are inside the corporate network.
