Cisco 300-820 Flashcards
Which complication does a NAT introduce in SDP for a SIP call?
A. Additional headers due to NAT encapsulation can cause the packet size to exceed the MTU.
B. When the client is behind a NAT they may be unable to determine the appropriate offset due to time zones.
C. The IP address specified in the connection data field may be an unrouteable internal address.
D. The encryption keys advertised in the SDP are only valid for clients not behind a NAT.
C
(https://www.examtopics.com/exams/cisco/300-820/view/)
A company already has a Cisco Unified Communications Manager for internal audio and video traffic, but it requires video communication with external partners and customers. It is important to ensure security for the deployment and the connectivity.
What must be set up to enable this requirement?
A. Cisco Unified Border Element and Cisco ASA Firewall B. Cisco Unified Border Element and Cisco Firepower Firewall C. Cisco Expressway-C and Cisco Expressway-E D. Cisco Expressway-C and Cisco Unified Border Element
C
When an Expressway-E is configured for static NAT, which Session Description Protocol attribute is modified to reflect the NAT address?
A. SDP b-line B. SIP record route C. SDP c-line D. SDP m-line
C
A company is installing Cisco Collaboration infrastructure and one of the requirements is that they must be able to communicate with many external parties that are using H.323 and SIP. Internally they want to register the endpoints only on SIP.
Which functionality would describe the feature that needs to be enabled and where to achieve this?
A. Interworking in Expressway-C B. Transcoding in Cisco Unified Communications Manager C. Transcoding in Expressway-C D. Interworking in Cisco Unified Communications Manager
A
What is a key configuration requirement for Hybrid Message Service High Availability deployment with multiple IM and Presence clusters?
A. You must have the Intercluster Sync Agent working across your IM and Presence clusters. B. You must have the Intercluster Lookup Service working across all of your IM and Presence clusters. C. Your IM and Presence Service clusters must have Multiple Device Messaging disabled. D. AXL service should be activated only on the publisher of each IM and Presence cluster.
A
The Cisco Sync Agent must be running on the database publisher node of each intercluster peer on the local and remote IM and Presence database publisher nodes
Cisco Collaboration endpoints are exchanging encrypted signaling messages.
What is one major complication in implementing NAT ALG for voice and video devices?
A. Internal endpoints cannot use addresses from the private address space. B. The NAT ALG cannot inspect the contents of encrypted signaling messages. C. NAT ALG introduces jitter in the voice path. D. Source addresses cannot provide the destination addresses that remote endpoints should use for return packets.
B
The NAT ALG cannot inspect the contents of encrypted signaling message - https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/srnd/collab11/collab11/security.html
What are two reasons why port 8443 is unreachable from the Internet to the Expressway-E? (Choose two.)
A. The MRA license is missing on the Expressway-E. B. The Unified Communications zone is down. C. Transform is not configured on Expressway-E. D. The SRV record for _cisco-uds is misconfigured. E. The firewall is blocking the port.
D E
Which media encryption mode can be configured on an Expressway zone?
A. Advanced Encryption Standard
B. IPsec
C. Triple Data Encryption Standard
D. force unencrypted
D
The encryption mode options are:
Force encrypted: All media to and from the zone/subzone must be encrypted. If the target system/endpoint is configured to not use encryption, then the call will be dropped.
Force unencrypted: All media must be unencrypted. If the target system/endpoint is configured to use encryption, then the call may be dropped; if it is configured to use Best effort then the call will fall back to unencrypted media.
Best effort: Use encryption if available, otherwise fall back to unencrypted media.
Auto: No specific media encryption policy is applied by the Expressway. Media encryption is purely dependent on the target system/endpoint requests. This is the default behavior and is equivalent to how the Expressway operated before this feature was introduced.
What is the purpose of a transform in the Expressway server?
A. A transform has the function as a neighbor zone in the Expressway. It creates a connection with another server. B. A transform changes the audio codec when the call goes through the Expressway. C. A transform is used to route calls to a destination. D. A transform changes an alias that matches certain criteria into another alias.
D
An organization with a domain name of example.com.
Which two SRV records are valid for a SIP and H.323 communication? (Choose two.)
A. _sips._tcp.example.com B. _sips._udp.example.com C. _h323ls._udp.example com D. _h323ls._tcp.example.com E. _collab-edge._tls.example.com
A C
What is the Cisco-recommended key length in bits for a Cisco Expressway certificate?
A. 1024 B. 2048 C. 4096 D. 8192
C
SIP TLS zones may fail to become active if certificates use a key length of 8192 bits. We recommend using certificates with a key length of 4096 bits.
(\d{3})(\d{3})(\d{3})(\d{3})
Refer to the exhibit. Which two numbers match the regular expression? (Choose two.)
A. d20d16d20d22 B. 2091652010224 C. 209165200225 D. d209d165d200d224 E. 209165200224
C E
A company has enabled ICE to optimize call flows and improve video quality between their Cisco Collaboration endpoints internally and externally.
For which reason would you see activity on the TURN server when a call is established between two external endpoints?
A. The video call is using encryption, which is not supported by ICE with CUCM 12.5 B. ICE cannot reduce the packet loss on the link C. A STUN cannot punch holes in the firewall D. The video call is using 4K resolution, which is not supported by ICE with CUCM 12.5
C
The answer is C “Those addresses (A, B, and C) populate the SIP SDP offer and answer as ICE candidates, and after the signaling has gone through, both endpoints will have the remote party ICE candidate addresses. It is at that point that the endpoints do a connectivity check by sending STUN messages to one another in an attempt to punch transport holes in the firewalls in order to establish media connectivity between peers.”
Which role does Call Policy play when preventing toll fraud on Expressways?
A. It controls which calls are allowed, which calls are rejected, and which calls are redirected to a different destination. B. It changes the calling and called number on a call. C. It changes the audio protocol used by a call through Expressways. D. It changes the audio codec used in a call through Expressways.
A
You can set up rules to control which calls are allowed, which calls are rejected, and which calls are to be redirected to a different destination. These rules are known as Call Policy (or Administrator Policy).
If Call Policy is enabled and has been configured, each time a call is made the Expressway will execute the policy in order to decide, based on the source and destination of the call, whether to:
* Proxy the call to its original destination.
* Redirect the call to a different destination or set of destinations.
* Reject the call.
What happens to the encrypted signaling traffic of a collaboration device if you place it inside a firewall with private IP addresses and try to make a call over IP without any collaboration infrastructure?
A. The signaling makes it back to the endpoint because the firewall is an application layer gateway and provides address translation. B. Encrypted IP traffic for collaboration devices always is trusted by the firewall. C. The signaling does not make it back to the endpoint because the firewall cannot inspect encrypted traffic. D. The signaling makes it back to the endpoint because the endpoint sent the private address to the external endpoint.
C
Which statement about scheduling Expressway backups is true?
A. It is not supported on the application. B. It is allowed from the application CLI of the Expressway only. C. It is allowed from the application CLI and GUI of the Expressway. D. It is allowed from the application GUI of the Expressway only.
A
Between which two DTMF relay methods does the Expressway support interworking? (Choose two.)
A. unsolicited notify B. RFC 2833 C. KPML D. passthrough E. H.245 user input indication
B E
When the Expressway is interworking a call between SIP and H.323, it also interworks the DTMF signaling, but only between RFC 2833 DTMF, and the H.245 user input indicators “dtmf” and “basicString”.
What allows endpoints behind a NAT to discover the paths through which they will pass media?
A. RTP B. TLS C. SNMP D. ICE
D
https://www.cisco.com/c/en/us/td/docs/solutions/PA/ICE/icepa125.html
Which two types of information does Cisco Expressway back up? (Choose two.)
A. call records B. log files C. IP addresses D. current call states E. security certificates
C E
Which connection does the traversal zone configuration define?
A. Expressway-E and Collaboration Endpoints B. Cisco UCS E-Series and Cisco UCM C. Cisco UC and Cisco Unified Presence Server D. Cisco Expressway-C and Cisco Expressway-E platforms
D
Which protocol should be used to verify the connectivity for different media paths found during a call using ICE?
A. STUN B. RTP C. SNMP D. TURN
A
Which SIP media encryption mode is applied by default for newly created zones in the Cisco Expressway?
A. Off B. Best Effort C. Auto D. Force Encrypted
C
Answer C: Auto - no specific media encryption policy is applied by the Expressway. Media encryption is purely dependent on the target system/endpoint requests. This is the default behavior and is equivalent to how the Expressway operated before this feature was introduced
Cisco media traversal technology has enabled a secure environment where internal video endpoints call and receive calls from external video endpoints. How does the Expressway-C and Expressway-E communicate?
A. Expressway-C establishes an outgoing request to Expressway-E, enabling the Expressway-E in the DMZ to notify the internal Expressway-C of an incoming call from an external endpoint. B. Internal endpoints are registered to Expressway-E in the DMZ. Expressway-C, which is also in the DMZ, will receive and make calls on behalf of Expressway- E because they are in the same network. C. Expressway-E establishes an outgoing request to Expressway-C, enabling the Expressway-C in the DMZ to notify the internal Expressway-E of an incoming call from an external endpoint. D. Internal endpoints are registered to Expressway-C in the DMZ. Expressway-E, which is also in the DMZ, will receive and make calls on behalf of Expressway- C because they are in the same network.
A
https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/expressway/config_guide/X12-5/exwy_b_mra-expressway-deployment-guide/exwy_b_mra- expressway-deployment-guide_chapter_00.html
Which dial plan component is configured in Expressway-C to route a call to the Cisco UCM?
A. call routing B. traversal subzone C. call policy D. search rule
D