1、The TTL field was originally designed to hold a time stamp, which was decremented by each visited router. The datagram was ( ) when the value became zero. However, for this scheme, all the machines must have synchronized clocks and must know how long it takes for a datagram to go from one machine to another. Today, this field is used mostly to control the ( ) number of hops (routers) visited by the datagram. When a source host sends the datagram, it (请作答此空) a number in this field. Each router that processes the datagram decrements this number by 1. If this value, after being decremented, is zero, the router discards the datagram.This field is needed because routing tables in the Internet can become corrupted.A datagram may travel between two or more routers for a long time without ever getting delivered to the ( ).This field limits the ( ) of a datagram.
A、controls
B、transmits
C、stores
D、receives
答案:C
答题解析:TTL的基本概念。
2、The TTL field was originally designed to hold a time stamp, which was decremented by each visited router. The datagram was ( ) when the value became zero. However, for this scheme, all the machines must have synchronized clocks and must know how long it takes for a datagram to go from one machine to another. Today, this field is used mostly to control the ( ) number of hops (routers) visited by the datagram. When a source host sends the datagram, it ( ) a number in this field. Each router that processes the datagram decrements this number by 1. If this value, after being decremented, is zero, the router discards the datagram.This field is needed because routing tables in the Internet can become corrupted.A datagram may travel between two or more routers for a long time without ever getting delivered to the (请作答此空).This field limits the ( ) of a datagram.
A、switch
B、router
C、source host
D、destination host
答案:D
答题解析:TTL的基本概念。
3、The TTL field was originally designed to hold a time stamp, which was decremented by each visited router. The datagram was ( ) when the value became zero. However, for this scheme, all the machines must have synchronized clocks and must know how long it takes for a datagram to go from one machine to another. Today, this field is used mostly to control the ( ) number of hops (routers) visited by the datagram. When a source host sends the datagram, it ( ) a number in this field. Each router that processes the datagram decrements this number by 1. If this value, after being decremented, is zero, the router discards the datagram.This field is needed because routing tables in the Internet can become corrupted.A datagram may travel between two or more routers for a long time without ever getting delivered to the ( ).This field limits the (请作答此空) of a datagram.
A、lifetime
B、moving time
C、receiving time
D、transmitting time
答案:A
答题解析:TTL的基本概念。
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