Images on Safari appearing as question marks

Sometimes, the images on certain web pages, appear as blue boxes 开发者_开发知识库with question marks.

Does it have to do with wrong markup or some file format that Safari can't recognize?

This is most likely caused by an image with the wrong src attribute. For instance, an image like this: <img src="link/to/non/existent/image.jpg" /> Would show the blue box with a question mark.

Well, recently I have found out that it's an issue connected to wrong DNS. Please open your Network Settings in Preference pane, then go to your active connection, press Advanced, go to DNS tab and try replacing DNS to for instance 8.8.8.8 It solved the issue for me