Q: Hi -- I have a late 2011 13" macbook pro that shipped with and runs Lion. Unfortunately, I do not have the install disks with me. Holding down D key does nothing. What can I do?

Power off hold D key and restart, continue to hold D key till you see the AHT icon, be patient it takes a while (2 minutes or so. After you get to the AHT screen let it do the probe and finish the probe. Then click test, if you want a more extensive test click Perform extended testing, this will take considerably longer. I just did this on my late 2011 13" running Lion 10.7.5 and it was fine.  Be patient, as your internet connection has a great deal to do with the length of time this will take.  If you have a wireless connection that could be "iffy" use an ethernet connection to eliminate the possibility of RF (radio Frequency) corruption.  Hope this helps. All the best SJP

If your Mac came originally with Lion Pre-Installed then there was NO discs included. Yes to run the Online AHT you need to hold down the D key at startup until you see a Spinning Globe in the center of the screen. you should also have the system Wired to your Router, Ethernet cable. WiFi may work and then it may not.

Press "Option" and "D" key together.

"Restart your computer, holding down the “D” key while the computer restarts.After your computer restarts, you should see the Apple Hardware Test chooser screen. If you don’t, Apple Hardware Test may not be available on your computer. You may be able to start Apple Hardware Test from the Internet. Reconnect your computer to the network, and then restart your computer while holding down both the Option and “D” keys."

http://support.apple.com/kb/PH4510

Best.

Not to argue with anyone, just my obsevation, and all posts are valid in my mind (though that may be questionable). When I did the D boot, I just pwered up holding D, never saw any progress wheel/bar, notta. It just popped up the AHT icn (chip looking sort of thing), and then the menu to do the AHT. Maybe there is a slight difference between builds? It did take a while to do this via wireless, although I usually use ethernetnet, as I happen to live in a place that has a  great quantity of RF traffic with a ton of construction RF going on.  All methods in this thread are valid and should be tried one by one, just keep in mind this is a slower process than downloading a web page, and patience is required for the connection to the mothership can vary.  Just a silly add on.  All the best to all, or if your from the southern US... best to all y'all:)

With a late 2011 MBP, if you hold down the option key at boot, you should get the network boot option.  From there you should be able to acces the Disk Utility where you can run diagnostics on your HD.  Yes, you need internet access, but it should work.

Try holding the Option key and the D key. This worked for me on a 27" mid 2011 iMac.