300-820 · Question #115
Cisco Jabber clients are failing to log in using Mobile and Remote Access. The administrator checked the Jabber problem report logs and saw that connections to the Expressway-E are being refused on…
The correct answer is B. The Unified Communications zone is down. C. The firewall is blocking the port. For Mobile and Remote Access (MRA), Jabber clients connect to Expressway-E on TCP port 8443 (HTTPS/XMPP). Two conditions can cause no response to TCP SYN packets from the internet: (B) the Unified Communications traversal zone on Expressway-E is down - without an active UC…
Question
Cisco Jabber clients are failing to log in using Mobile and Remote Access. The administrator checked the Jabber problem report logs and saw that connections to the Expressway-E are being refused on TCP port 8443. From a packet capture run on the Jabber client while attempting to log in, there is no response to the TCP SYN packets sent to the Expressway-E by Jabber. Which two reasons are causing the Expressway-E to be unreachable on port 8443 from the internet? (Choose two.)
Options
- AThe Jabber clients using an outdated version.
- BThe Unified Communications zone is down.
- CThe firewall is blocking the port.
- DThe certificate for Jabber is expired.
- EThe SRV record for _cisco-uds is misconfigured.
How the community answered
(38 responses)- A11% (4)
- B82% (31)
- D5% (2)
- E3% (1)
Explanation
For Mobile and Remote Access (MRA), Jabber clients connect to Expressway-E on TCP port 8443 (HTTPS/XMPP). Two conditions can cause no response to TCP SYN packets from the internet: (B) the Unified Communications traversal zone on Expressway-E is down - without an active UC zone, Expressway-E will not accept or process MRA connections on that port; and (C) the firewall in front of Expressway-E is blocking TCP 8443 inbound from the internet - a blocked SYN gets no reply, which exactly matches the observed symptom. Jabber client version, certificate expiry, and _cisco-uds SRV records affect different parts of the login flow and would not produce the 'no response to SYN' behavior.
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