Free Cisco 642-785 Exam Dumps Questions & Answers

An MPLS VPN customer with managed CE services recently made some changes to their call manager configurations. Now the customer reports that their VoIP traffic voice quality is very poor. What could be a cause of the problem?

• A.The traffic shaping rate for the VoIP traffic class is too low.
• B.The VoIP traffic class is not being policed at the CE router egress.
• C.RTP header compression is used for the VoIP traffic class.
• D.The customer changed the codec used for voice compression from G.729 to G.711.
• E.The VoIP traffic is being marked as DSCP EF.

Where would you apply WRED to avoid congestion and poor QoS from oversubscription of the network?

• A.wherever there is a potential bottleneck
• B.wherever there is a potential bottleneck and most traffic is voice
• C.wherever there is a potential bottleneck and most traffic is TCP
• D.wherever there is a potential bottleneck and most traffic is UDP
• E.wherever there is a potential bottleneck and traffic is delay-intolerant

What three statements about WRED are true? (Choose three.)

• A.WRED is a congestion avoidance technique.
• B.Using WRED on the edge devices (CE, PE) is an effective method of implementing
  congestion avoidance in the service provider network, because it avoids the congestion prior to reaching the core.
• C.WRED should always be used in traffic classes that support a MIX of realtime UDP and TCP traffic.
• D.WRED employs a weighted method for determining which packets to drop to avoid congestion. Packets with a higher precedence are less likely to be dropped.
• E.Using WRED will necessitate a large number of dropped packets.

Refer to the exhibit.

A service provider moved from a three-class service provider QoS model to a four-class service provider QoS model. A new class of service called CRITICAL-B was created to support traffic with a DSCP marking of AF31. A customer reports that the traffic in the CRITICAL-B class is having problems. What step should the service provider take to correct this issue?

• A.The class map for CRITICAL-B should have a DSCP value of 28.
• B.The max-reserved-bandwidth command must be used to allocate more bandwidth than allowed by default.
• C.The policy map should be updated to move the BULK class to the bottom of the policy.
• D.The CRITICAL-A class should change from match-all to match-any.

Within a QoS policy-map configuration, one of the traffic classes is configured with the random-detect dscp-based configuration command. What will that command accomplish?

• A.decreases the probability of congestion by selectively dropping TCP packets before the queue is full
• B.decreases congestion by avoiding global UDP synchronization
• C.provides congestion avoidance by selectively delaying the delivery of packets with lower DSCP priority
• D.provides congestion management by queueing the traffic using LLQ
• E.provides congestion management by queueing the traffic using CBWFQ