关于域名解析说法错误的是( )。
A．名字服务器也构成层次结构
B．域名服务器是域名解析系统的核心
C．反复解析就是反复要求名字服务器系统一次性给出全部解析
D．域名解析是在服务器树中的一条单向路径
参考答案：C
解析： 主机名与IP地址的映射是借助于一组既独立。又协作的域名服务器完成的。因特网中存在大量的域名服务器，域名服务器是域名解析系统的核心。名字服务器也构成一定的层次结构。域名解析采用自项向下的算法，从根服务器到叶服务器，在其间的某一个结点上实现域名解析。由于树形结构的上下管辖关系，域名解析只走一条从树中某结点开始到另一结点的一条自顶向下的单向路径，不会回溯，也不会遍历整个树结构。反复解析就是每次请求一个服务器，不行再请求其他服务器。
| 完形填空。 |
| I'm taking my family to some other countries for a trip. My wife and I, and our two children are all 1 . My older brother will 2 with us, too. He never went to other countries 3 . He is even more 4 than the children. My father is old now, so he wants to stay at home to 5 the house. We're on the train to New York now, and then we will 6 a ship to Europe. England will be the first place for us to visit. After visiting there, we will go to some other countries to do some sightseeing. When we 7 France, we'll go to different places either by train or by bus. Then we're going to fly home. It took us a long time to 8 where to go, but I think we'll have a very interesting trip. We'll go to England, France and Italy. We also talked about 9 we would go to Europe. At first we wanted to fly there because it would be faster and 10 a lot of time for us, but my brother liked traveling boat trips, and the children liked ship trips, too. |
| ( )1. A. walking ( )2. A. join ( )3. A. ago ( )4. A. excited ( )5. A. put away ( )6. A. have ( )7. A. arrive in ( )8. A. make ( )9. A. what ( )10. A. take | B. visiting B. travel B. later B. worried B. build up B. bring B. leave for B. guess B. how B. spend | C. going C. chat C. recently C. interested C. look after C. take C. arrive at C. find C. where C. have | D. taking D. stay D. before D. frightened D. clean up D. buy D. live in D. plan D. why D. save |
