Exam 300-820 topic 1 question 167 discussion

Actual exam question from Cisco's 300-820

Question #: 167
Topic #: 1

Refer to the exhibit. An engineer must configure a B2B traversal zone. Trusted certification authority and server certificates are uploaded to Cisco Expressway-C and Expressway-E servers. After the traversal zone configuration is completed in Expressway-C, the error message in the exhibit appears. What are the two reasons for the error? (Choose two.)

A. The peer 1 address in Expressway-C must be replaced by the FQDN of Expressway-C.
B. The peer 1 address in Expressway-C is not the FADN of Expressway-E.
C. The communication port is not set to 7001.
D. The FQDN of Expressway-E cannot be resolved by the DNS server.
E. The traversal zone TLS verify subject name in Expressway-E does not match the FQDN of Expressway-C.

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Suggested Answer: BE 🗳️

by Cayne_Collins at July 19, 2024, 8:17 p.m.

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collaboratorgator

1 month, 2 weeks ago

Selected Answer: BE

With TLS verify mode set to On, ensure the Peer Address configured matches the CN or SAN of the presented certificate by Expressway-E With TLS verify mode set to On, ensure the TLS verify subject name configured matches the CN or SAN of the presented certificate by Expressway-C https://www.cisco.com/c/en/us/support/docs/unified-communications/expressway/213864-configure-business-to-business-audio-and.html#toc-hId--516449206

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iamnoone

4 months, 4 weeks ago

Selected Answer: BE

Will go with B and E. https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/expressway/config_guide/X14-0/basic_config/exwy_b_cisco-expressway-e-and-expressway-c-basic-configuration-deployment-guide-x14-0/exwy_m_routing-configuration.html#concept_5CACB904BBC11E766FDB34D20BE12C9A

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TheBabu

1 year ago

Selected Answer: BE

A is wrong because the FQDN of Expressway-E should be used in the peer address field. B is correct, assuming "FADN" is just a typo. C is not an issue, you don't necessarily need to start by using 7001. As long as E is listening on 7002, this works (tested in the lab). D does not apply here because they're not using the FQDN currently. E makes sense, they're not showing the config on the E side, but if you put the wrong "TLS verify subject name" there you will get a TLS connection failure. Going for B and E here.

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Cayne_Collins

1 year ago

I am leaning more towards B and C on this one. Literally answers A and B are contradictory to each other. Unless this setup has multiple traversal zones, and this isnt the first one, they should be using port 7001.

upvoted 2 times

collaboratorgator

1 month, 2 weeks ago

A separate traversal zone has to be configured to route the B2B traffic between Expressway-C and Expressway-E. This is a standard traversal zone configuration, but similar as with the SIP trunk on CUCM a different port then the port used by the UC Traversal zone for Edge traffic must be configured. The standard port for the UC Traversal zone is 7001. For the B2B Traversal zone, you can e.g configure 7003. https://www.cisco.com/c/en/us/support/docs/unified-communications/expressway/213864-configure-business-to-business-audio-and.html#toc-hId--516449206

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