CCNP Voice FAQ: Classification, Marking, and NBAR
Q1. Which of the following is not a valid classification traffic descriptor?
A. Incoming interface
B. Traffic path
C. IP precedence or DSCP value
D. Source or destination address
Q2. Which of the following is not considered a data link layer QoS marking field?
B. Frame Relay DE
D. ATM CLP
Q3. Which of the following CoS values is reserved for internetwork and network control?
Q4. Which of the following is the Frame Relay QoS marking field?
Q5. Which of the following is true about the MPLS header and its EXP field size?
A. The MPLS header is 2 bytes and the EXP field is 3 bits long.
B. The MPLS header is 2 bytes and the EXP field is 6 bits long.
C. The MPLS header is 4 bytes and the EXP field is 6 bits long.
D. The MPLS header is 4 bytes and the EXP field is 3 bits long.
Q6. What is “an externally observable forwarding behavior of a network node toward a group of IP packets that have the same DSCP value”?
C. Service class
Q7. Which of the following is not a DSCP PHB?
A. Default PHB
B. Class selector PHB
C. Assured forwarding PHB
D. Cisco Express Forwarding PHB
Q8. Which of the following has the higher drop probability?
D. They all have the same drop probability.
Q9. Which of the following is not a common voice and video service class?
A. Voice bearer (or payload)
B. Voice and video conferencing
C. Video payload
D. Voice and video signaling
Q10. At which of the following places is the trust boundary not implemented?
A. Core switch
B. Distribution switch
C. Access switch
D. End system
Q11. Which of the following is not a service that NBAR provides?
A. Protocol discovery
B. Collection of traffic statistics
C. Traffic classification
D. Traffic policing
Q12. Which of the following is true about loading a new PDLM?
A. You need to upgrade the IOS and reload your router.
B. You need to upgrade the IOS, but a reload is not necessary.
C. You do not need to upgrade the IOS, but a router reload is necessary.
D. You do not need to upgrade the IOS and do not need to reload either.
Q13. Which of the following is not an NBAR limitation?
A. NBAR can handle only up to 24 concurrent URLs.
B. NBAR analyzes only the first 400 bytes of the packet.
C. NBAR is not supported on interfaces in which tunneling or encryption is used.
D. NBAR is dependent on CEF.
Q14. Which of the following commands uses the NBAR classification feature within a class map?
A. match protocol protocol-name
B. match nbar protocol protocol-name
C. match protocol-name
D. match nbar protocol-name
Q15. What does the * character mean in a regular expression?
A. Match one of a choice of characters.
B. Match any zero or more characters in this position.
C. Match any one character in this position.
D. It means OR.
Q16. Define and explain classification.
Q17. Define and explain marking.
Q18. What is the marker field on the 802.1Q/P frame called?
Q19. What are the names and definitions for CoS values 0 through 7?
Q20. Which one of the DSCP PHBs provides backward compatibility with ToS-based IP precedence?
Q21. What are the four DiffServ (DSCP) PHBs?
Default PHB—Used for best-effort service (000—)
Class selector PHB—Used for backward compatibility with non-DiffServ-compliant devices (—000)
Assured forwarding (AF) PHB—Used for guaranteed bandwidth services
(001—, 010—, 011—, 100—)
Expedited forwarding (EF) PHB—Used for low-delay service (101110)
Q22. How is compatibility between MPLS and network layer QoS achieved?
Q23.What is a QoS service class?
Q24. What is a trust boundary?
Q25. What is NBAR?
Answer: Network Based Application Recognition (NBAR) is a classification and protocol discovery tool or feature. You can use NBAR to perform three tasks:
- Protocol discovery
- Traffic statistics collection
- Traffic classification
Q26. Name at least three limitations of NBAR
Answer: NBAR has several limitations:
- NBAR does not function on Fast EtherChannel and on interfaces that are configured to use encryption or tunneling.
- NBAR can only handle up to 24 concurrent URLs, hosts, or MIME types.
- NBAR analyzes only the first 400 bytes of the packet.
- NBAR supports only CEF and does not work if another switching mode is used.
Multicast packets, fragmented packets, and packets that are associated with secure HTTP (URL, host, or MIME classification) are not supported.
- NBAR does not analyze or recognize the traffic that is destined to or emanated from the router running NBAR.
Q27. List application support for NBAR.
Q28. What is PDLM?
Q29. What types of RTP payload classification does NBAR offer?
Q30. Which match command within a class map allows you to identify FastTrack peer-to-peer protocols?