Chapter 11 Practice Test Answers
1. A and C. ISDN and T-carrier connections are offered by telephone carriers.
2. False. Multiplexers aggregate multiple channels and treat them as a single trunk.
3. B. FDDI uses a dual–ring, counter-rotating configuration to self-heal any failures in the ring.
4. A. ATM uses a 53-byte fixed cell to transmit data.
5. A and D. ATM Adaptation layer (AAL) is responsible for feeding information either up or down to other ATM layers.
6. A. ISDN is commonly sold at speeds of 128 Kbps.
7. D. SONet is capable of speeds up to 39813.1 Mbps, exceeding all other technologies and making it appropriate for Internet backbone transmission.
8. C. The committed information rate (CIR) determines the minimum available bandwidth.
9. D. The multiplexer aggregates many channels into a single trunk channel.
10. B. Packet switching allows data to take the best path, but not always the same path, and therefore packet switching also permits data to use any available path should there be a network failure.
11. B. A WAN is characterized by large geographical distances between nodes.
12. E, F, and G. WAN technologies operate at the lowest three layers of the OSI Model.
13. D. ATM supports transmission speeds ranging from 1.544 Mbps to 622 Mbps.
14. D. PSTN uses circuit switched networks to carry telephone calls.
15. B. A virtual path connection aggregates virtual channel connections into a trunk.
16. A. To support a frame relay internetwork, all sites must have a CSU/DSU. Most sites will have two CSU/DSU devices if the sites are interconnected.
17. C. PRI (primary rate interface) offers 1.544 Mbps, while BRI (basic rate interface) offers 128 Kbps.
18. D. ATM is commonly used for video conferencing within the internetwork.
19. A. Circuit switched WAN connections provide a guaranteed bandwidth allocation.
20. D. The data channel (D channel) carries control information.
21. B. SDH set global standards for transmission.