如果企图访问这部分空间，无论读写都会造成某种运行时失效。
Any attempt to access that area for reading or writing causes some kind of runtime failure.
例如，只有在由于所访问的页面已经被交换到磁盘上而发生页面失效的情况时，PPE 才会接收到一个中断。
Only when a page fault is hit, for example, because the accessed page has been swapped out to disk, does the PPE receive an interrupt.
当用户访问这个页面时，浏览器首先检查本地缓存，以确定本地文件是否已经失效。
When a user accesses this page, the browser first checks the local cache to determine if the local files have expired.
因为不知道爬行器什么时候会访问您的站点，频繁地停机(即“维护时间窗”)会有风险，如果爬行器在站点停机时到来，它就会认为站点是失效的，从而转到其他站点去。
Because you don't know when the spider will visit, it's risky to have frequent down times or "maintenance Windows" — the spider will move on to another site.
如果安全措施太少，您唯一的防御系统将会失效，从而让外人能够访问检查点之后的所有数据。
Too little security, and your only defense system will be thwarted and allow full access to everything inside that checkpoint.
对于HTTP，此类交互建模为POST请求，因此这类请求将使所访问的资源的缓存项失效。
For HTTP, such an interaction is modeled as a POST request, so this type of request invalidates the cache entries for the addressed resource.
如果你在set访问器里拼错属性的名字，或者你重命名了属性，那么它会悄然失效。
If you misspell the property name in the setter, or rename the property, then it will silently fail.
在高性能路由器上设计与实现ARP协议时存在三个关键问题：ARP表的一致性、ARP表访问失效和ARP协议的安全。
When designing and implementing the ARP protocol in high-end routers, we must deal with three key issues: consistency of the ARP table, ARP access failure and ARP security.
US B驱动器功能失效是一个轻量级的应用程序，它可以禁用您的计算机上的所有usb端口的访问。
USB Drive Disabler is a lightweight application that can disable access to all USB ports on your computer.
如果某个模块成员的类型提升失效，而您没有完全限定该成员，则无意中可能会访问另一个编程元素。
If type promotion is defeated for a module member and you do not fully qualify that member, you could inadvertently access a different programming element.
如果某个模块成员的类型提升失效，而您没有完全限定该成员，则无意中可能会访问另一个编程元素。
If type promotion is defeated for a module member and you do not fully qualify that member, you could inadvertently access a different programming element.
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