300-820 practice test

1. Question 1 · 1

   Which complication does a NAT introduce in SDP for a SIP call?

   Choose one answer.

   • Additional headers due to NAT encapsulation can cause the packet size to exceed the MTU.
   • When the client is behind a NAT they may be unable to determine the appropriate offset due to time zones.
   • The IP address specified in the connection data field may be an unrouteable internal address.
   • The encryption keys advertised in the SDP are only valid for clients not behind a NAT.

2. Question 2 · 1

   An organization with a domain name of example.com. Which two SRV records are valid for a SIP and H.323 communication? (Choose two.)

   Choose all answers that apply.

   • _sips._tcp.example.com
   • _sips._udp.example.com
   • _h323ls._udp.example com
   • _h323ls._tcp.example.com
   • _collab-edge._tls.example.com

3. Question 3 · 1

   When the network requirements are configured for a new Video Mesh deployment, which firewall ports are required so that Video Mesh cascade signaling succeeds?

   Choose one answer.

   • TCP 443 and 444
   • TCP 443 and 8443
   • UDP 5004 and 5005
   • UDP 33432 through 33433

4. Question 4 · 1

   Which 16-digit number is unique to a serial number and is used to enable the system?

   Choose one answer.

   • RMS license key
   • option key
   • release key
   • Expressway series

5. Question 5 · 1

   Refer to the exhibit. What are “Type” field values for this Expressway servers zone configuration?

   Choose one answer.

   

   • Expressway-C “DNS”, Expressway-E “Traversal server”
   • Expressway-C “Traversal server”, Expressway-E “Traversal client”
   • Expressway-C “Neighbor”, Expressway-E “Neighbor”
   • Expressway-C “Traversal client”, Expressway-E “Traversal server”

6. Question 6 · 1

   An engineer reviews the configuration of a pair of Expressway servers for a company with the domain example.com. The company allows toll fraud calls to reach the Cisco UCM only when it expects externally registered devices to call internal 5-digit extensions. The search history shows that the fraudulent calls have a destination URI of 8 or more digits and several domains. What must the engineer configure to prevent all toll fraud calls from going past the Expressway-E to the internal network?

   Choose one answer.

   • search rules to only route calls with a destination URI of 5 to 8 digits long on the Expressway-E
   • CPL that blocks calls with a destination domain other than example.com on the Expressway-C.
   • search rules to only route calls with a destination domain of example.com on the Expressway-E
   • CPL to block calls with a destination URI with 8 or more digits on the Expressway-E

7. Question 7 · 1

   Which two internal SIP endpoints behind a firewall place calls to external devices? (Choose two.)

   Choose all answers that apply.

   • An Expressway-C communicates with the internal endpoint and forwards the media to and from an Expressway-E.
   • A Cisco Endpoint is configured with a publicly routable static NAT SIP address to advertise instead of is private IP address.
   • An Expressway-C communicates directly with the remote party using the ICE protocol
   • An Expressway-E is used as a VPN server to allow remote SIP edge servers to connect calls
   • An Expressway-C rewrites the SIP SDP to advertise its own IP address to the external party.

8. Question 8 · 1

   Which mechanism does TLS use to validate identity?

   Choose one answer.

   • server certificate
   • shared secret
   • username and a password
   • IP address of the peer

9. Question 9 · 1

   Refer to the exhibit. Call policy rules on an Expressway-E prevent external callers from the internet from calling a VIP whose URI is vip@cisco.com. Which additional configuration setting is required for this call policy to function as intended?

   Choose one answer.

   

   • The default zone on the Expressway-E must not be configured to treat as authenticated.
   • A search rule must be configured with an extract match for vip@cisco.com to pass the call to the Expressway-C.
   • The Cisco TelePresence endpoint registered with the URI vip@cisco.com must be set in “do not disturb” mode.
   • SIP TLS must be disabled on the Expressway-E.

10. Question 10 · 1

    An engineer configures a Cisco Collaboration environment to use Mobile and Remote Access for external access for company users. The engineer uses OAuth with refresh on the Cisco UCM SIP lines for extra security and improved user experience. During the setup, Mobile and Remote Access does not work, it is enabled on the Cisco UCM and Cisco Expressways. SIP trunks on ports 5090 and 5091 are configured to avoid conflicts with other SIP trunks between internal Cisco UCM clusters. The traversal zone also uses port 6500. The traversal zone between Expressways shows no errors, and the requests hit Expressway-E from the Internet. What is the reason that the solution does not work?

    Choose one answer.

    • Mobile and Remote Access does not support OAuth with refresh with this configuration,
    • The default port for Mobile and Remote Access is 6001. Therefore, the traversal port must be port 6001 for Mobile and Remote Access to work.
    • The default port for Mobile and Remote Access is 6500, which creates a conflict with the existing traversal zone port.
    • The default port for Mobile and Remote Access is 5091, which creates a conflict with the existing SIP trunks.

11. Question 11 · 1

    What is the Cisco-recommended key length in bits for a Cisco Expressway certificate?

    Choose one answer.

    • 1024
    • 2048
    • 4096
    • 8192

12. Question 12 · 1

    Cisco Collaboration endpoints are exchanging encrypted signaling messages. What is one complication in implementing NAT ALG for voice and video devices?

    Choose one answer.

    • NAT ALG is not compatible with the H.323 signaling protocol.
    • NAT ALG introduces latency in the media path.
    • The NAT ALG cannot inspect the contents of encrypted signaling messages.
    • NAT ALG requires the use of NAT reflection, which may not be supported on all firewalls.

13. Question 13 · 1

    How are Cisco Webex Video Mesh deployments supported?

    Choose one answer.

    • Video Mesh Dual NIC are supported in demilitarized deployments.
    • Mixed Single NIC and Dual NIC are supported in the same data center deployments.
    • Clustering Video Mesh Nodes over the WAN are supported if Round Trip Time is low.
    • IPv6 and IPv4 deployments are supported for Video Mesh clusters.

14. Question 14 · 1

    An administrator is deploying Cisco Expressways for Mobile and Remote Access. The registration domain is “example.com”, and the Expressway-E FQDN is “expe.example.com”. Cisco Jabber clients on the internet cannot discover services via DNS lookup. Which SRV records must be configured in the public DNS to allow Service Discovery?

    Choose one answer.

    • _collab-edge._tls.example.com
    • _cisco-uds_tcp.expe.example.com
    • _cisco-uds_tcp.example.com
    • _collab-edge_tls.expe.example.com

15. Question 15 · 1

    How is the communication routed in a Hybrid deployment so that people on Cisco Cloud-Based IM are able to communicate with Cisco Jabber users in the on-premises environment?

    Choose one answer.

    • The Expressway-C enables a connection directly with the Cisco Webex Cloud to enable the hybrid service and allow the two services to communicate.
    • The Expressway-E located in the DMZ establishes a connection with the Cisco Webex Cloud to enable the hybrid service and allow the two services to communicate.
    • The Cisco Unified IM and Presence server establishes a connection using the outgoing path through the Cisco Expressways that terminates in the Cisco Webex Cloud to create the hybrid environment that links the two services together.
    • The Cisco UC server establishes a connection using the outgoing path through the Cisco Expressways that terminates in the Cisco Webex Cloud to create the hybrid environment that links the two services together.

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