t three factors that affect local network design. What are the three basic underlying considerations in the design of a long-distance (toll) network? What is the fallacy of providing just one high-capacity trunk group across the United States to serve all major population centers by means of tributaries off the main trunk? How can the utilization factor on trunks be improved? For long-distance (toll) switching centers, what is the principal factor in the place- ment of such exchanges (differing from local exchange placement substantially)? 6. How are the highest levels of a national hierarchical network connected, and why is this approach used? On a long-distance toll connection, why must the number of links in tandem be limited? 8. What type of routing is used on the majority of international connections? 9. Name two principal factors used in deciding how many and where long-distance (toll) exchanges will be located in a given geographic area. 10. Discuss the impacts of fan-outs on the number of hierarchical levels. LOCAL AND LONG-DISTANCE NETWORKS 11. Name the three principal bases required at the outset for the design of a long- distance network. 12. Once the hierarchical levels have been established and all node locations identified, what is assembled next? 13. Define a final route. 14. A grade of service no greater than % per link is recommended on a final route. 15. There are two generic types of routing schemes. What are they? 16. Name three different types of dynamic routing and explain each in one sentence. What is crankback? 18. Give an example of state-dependent routing. 19. What is the principal cause of echo in the telephone network? 20. What causes singing in the telephone network? Differentiate balance return loss from the point of view of stability (singing) from echo return loss. 22. How can we control echo? (Two answers required). 23. The stability of a telephone connection depends on three factors. Give two of these factors. 24. Based on the new loss plan for North America for the digital netwo