单项选择题
Originally introduced by Netscape Communications, (1) are a general mechanism which HTTP Server side applications, such as CGI (2) , can use to both store and retrieve information on the HTTP (2) side of the connection. Basically, Cookies can be used to compensate for the (4) nature of HTTP. The addition of a simple, persistent, client-side state significantly extends the capabilities of WWW-based (5) .
Melissa and LoveLetter made use of the trust that exists between friends or colleagues. Imagine receiving an (6) from a friend who asks you to open it. This is what happens with Melissa and several other similar email (7) . Upon running, such worms usually proceed to send themselves out to email addresses from the victim’s address book, previous emails, web pages (8) .
As administrators seek to block dangerous email attachments through the recognition of well-known (9) , virus writers use other extensions to circumvent such protection. Executable (.exe) files are renamed to .bat and .cmd plus a whole list of other extensions and will still run and successfully infect target users.
Frequently, hackers try to penetrate networks by sending an attachment that looks like a flash movie, which, while displaying some cute animation, simultaneously runs commands in the background to steal your passwords and give the (10) access to your network.
Networks can be interconnected by different devices. In the physical layer, networks can be connected by (11) or hubs, which just move the bits from one network to an identical network. One layer up we find bridges and switches, which operate at data link layer. They can accept (12) ,examine the MAC address, and forward the frames to a different network while doing minor protocol translation in the process. In the network layer, we have routers that can connect two networks. If two networks have (13) network layer, the router may be able to translate between the packer formats. In the transport layer we find transport gateway, which can interface between two transport connections. Finally, in the application layer, application gateways translate message (14) . As an example, gateways between Internet e-mail and X.400 e-mail must (15) the e-mail message and change various header fields.
The purpose of the requirements definition phase is to produce a clear, complete, consistent, and testable (16) of the technical requirements for the software product.
During the requirements definition phase, the requirements definition team uses an iterative process to expand a broad statement of the system requirements into a complete and detailed specification of each function that the software must perform and each _( 17) that it must meet. The starting point is usually a set of high level requirements from the (18) that describe the project or problem.
In either case, the requirements definition team formulates an overall concept for the system and then defines (19) showing how the system will be operated publishes the system and operations concept document and conducts a system concept review (SCR).
Following the SCR, the team derives (20) requirements for the system from the high level requirements and the system and operations concept. Using structured or object-oriented analysis, the team specifies the software functions and algorithms needed to satisfy each detailed requirement.
The Rational Unified Process (RUP) is a software engineering process, which captures many of best practices in modern software development. The notions of (21) and scenarios have been proven to be an excellent way to capture function requirements. RUP can be described in two dimensions - time and content. In the time dimension, the software lifecycle is broken into cycles. Each cycle is divided into four consecutive (22) which is concluded with a well-defined (23) and can be further broken down into (24) - a complete development loop resulting in a release of an executable product, a subset of the final product under development, which grows incrementally to become the final system. The content structure refers to the disciplines, which group (25) logically by nature.
Most computer systems are (26) to two different groups of attacks: Insider attacks and outsider attacks. A system that is known to be (27) to an outsider attack by preventing (28) from outside can still be vulnerable to the insider attacks accomplished by abusive usage of (29) users. Detecting such abusive usage as well as attacks by outsides not only provides information on damage assessment, but also helps to prevent future attacks. These attacks are usually (30) by tools referred to as Intrusion Detection Systems.
Soon, more of the information we receive via the Internet could come (31) in digital wrappers.
Wrappers are made up (32) software code that's targeted to do specific things with the data (33) within them, such as helping to define queries for search engines. They also keep (34) from (35) access to that code.
A typical (36) language contains an applicative sub-language which approximates the mathematical abstractions of "timeless" functions applied to' "spaceless" values, where the actual operation sequences and use of storage space during expression evaluation are organized behind the (37) . In this setting, values are data structures of low volume, typically a few computer words or less, which means that an illusion of spacelessness can be realized by having (38) results during expression evaluation stored at the discretion of the language implementation, and effecting parameter (39) and (40) operations through value copying.