Quality of Service Exam (QoS)
Exam: 642-641
Demo Edition
© 2008 - 2009 Test Killer, LTD All Rights Reserved
642-641
1
http://www.testkiller.com
http://www.troytec.com
QUESTION: 1
Per-VC congestion avoidance discard at Layer 2 has what consequence when the ingress
ATM interface discards a fragment?
A. Incomplete data packets are sent and the entire data packet must be resent.
B. The entire data packet is discarded at the ingress interface and must be resent.
C. Incomplete data packets are sent and the discarded packet fragments must be resent.
D. Data packets may be sent in cells that are out of order, causing the entire packet to be
resent.
Answer: D
QUESTION: 2
Why do real-time applications like VoIP require better service than traditional best effort
services? (Choose three)
A. These applications are sensitive to jitter.
B. These applications are sensitive to delays.
C. Real-time applications are sensitive to packet drops.
D. Real-time applications are typically non-interactive and use mostly bulk data transfer.
E. Real-time applications typically require RSVP which cannot be run on a network using
best-effort services.
Answer: A, B, E
QUESTION: 3
Which statement is true about policing traffic conditions in IP QoS?
A. Policing reorders transmit queues to offer priority service to specific traffic flows.
B. Policing utilizes buffers to delay excessive traffic when the flow is higher than expected.
C. Policing techniques monitor network traffic loads in an effort to anticipate and avoid
congestion.
D. Policing allows the network administrators to traffic engineer paths through the network
for application flows.
E. Policing is the ability to control bursts and conform traffic to ensure certain traffic types
receive specified amounts of bandwidth.
Answer: E
642-641
2
http://www.testkiller.com
http://www.troytec.com
QUESTION: 4
What is a limiting factor of IntServ scalability in large networks?
A. IntServ admission control must be implemented loca