From Apple KB
If you happen to encounter a situation in which you cannot start from the Recovery HD, such as your hard drive stopped responding or you installed a new hard drive without Mac OS X installed, new Mac models introduced after public availability of OS X Lion automatically use the Lion Internet Recovery feature if the Recovery HD (Command-R method above) doesn’t work. Lion Internet Recovery lets you start your Mac directly from Apple’s Servers. The system runs a quick test of your memory and hard drive to ensure there are no hardware issues. Lion Internet Recovery presents a limited interface at first, with only the ability to select your preferred Wi-Fi network and, if needed, enter the WPA passphrase. Next, Lion Internet Recovery will download and start from a Recovery HD image. From there, you are offered all the same utilities and functions described above.
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