Intermittent exception: java.net.UnknownHostException: profile.ak.fbcdn.net

I try to retrieve a picture from e.g

http://graph.facebook.com/btaylor/picture

using the following code:

DefaultHttpClient httpClient = new DefaultHttpClient();
HttpGet request = new HttpGet(urlString);
HttpResponse response = httpClient.execute(request);
return response.getEntity().getContent();

but occasionally I get the exception

java.net.UnknownHostException: profile.ak.fbcdn.net

Why is this?

Edit: by "occasionally", I mean that it happens often enough that I know the reason is not "My internet 开发者_运维问答is down" or "Facebook is down."

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If your device is connected on WiFi, could be due to this issue where the WiFi enters sleep mode.

http://www.boygeniusreport.com/2010/07/14/some-nexus-one-users-experiencing-wi-fi-connectivity-issues/

In my case, I see in the log:

D/WifiService( 1087): setting ACTION_DEVICE_IDLE timer for 900000ms

Then 15 minutes later, the WiFi is turned off.

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Using an emulator, there are some known network limitations, However on device it works fine. So, are you using an emulator?

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This was happening when I was testing in Simulator if I had a VPN connection open on the machine I was running the simulator on. Once I disconnected from VPN the exception is no longer generated