In computing, passwords are commonly used to limit access to official users. Yet the widespread use of passwords has serious drawbacks. Office workers now have to remember an average of twelve system passwords. In theory they should use different passwords for each site, but in reality these would be impossible to remember, so many people use the same password for all.
An additional problem is that the majority use simple words such as "hello", or names of family members, instead of more secure combinations of numbers and letters, such as 6ANV76Y. This permits computer hackers to download dictionaries and quickly find the word that allows them access.
When system users forget their passwords there is extra expense in supplying new ones, while if people are forced to change passwords frequently they often write them down, making systems even less secure. Therefore, it is clear that the idea of passwords, which have been used as security devices for thousa
A. They do not ensure security.
B. They are difficult to remember.
C. They have to be changed frequently.
D. They limit computer accessibility.
The grid computing is a new (66) technology connecting the distributed and (67) resources to the high-speed network and integrating a super-computer of processing capacity. The significance and architecture of the grid computing is explained. Several kernel technology such as OGSI, resource management, task management, task scheduling, high rate communication and security are described. Aiming at the particularity of the grid computing environment a mechanism similar to the technology of the search engine is designed to registry, discovery and (68) the resources in the grid. The whole model of the resource management is built by connecting task manager in the local resource management system to others with P2P model. The task may migrate among the task managers in order to (69) the load. The task users summit may be executed in relatively tight resource set, which will not only decrease the total communication overheads of the whole task but also (7
A. concentrative
B. distributed
C. aggregate
D. distributing
At a basic level,cloud computing is simply a means of delivering ITresources as ____(71)___.Almost all IT resources can be belivered as a cloud service:applications,compute power,storage capacity,networking,programming tools,even communication services and collaboration ____(72)____. Cloud computing began as large-scale Internet service providers such as Google,Amazon,and others built out their infrastructure.Anarchitecture emerged:massively scaled,____(73)____ distributed system resources,abstracted as virtual IT services and managed as continuously configured,pooled resources.In this architecture,the data is mostly resident on ___(74)___ "somewhere on the Internet" and the application runs on both the "cloud servers" and the user’s browser. Both clouds and grids are built to scale horizontally very efficiently.Both are built to withstand failures of ___(75)___ elements or nodes.Both are charged on a per-use basis.But while grids typically process batch
A. horizontally
B. vertically
C. inclined
D. decreasingly
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