The company posted notice of the attack on its Web page that the attack started at 4:05 GMT today with a brief explanation of the problem.

"Unfortunately, the DDoS attack from yesterday returned in a different form this morning and affected site-wide performance," the site says. "The good news is that we were able to mitigate it quickly and performance returned to normal around 11:15 [GMT]. We are continuing to monitor the situation closely."

The company still doesn't know why it was attacked, but speculation is it was an attempt to muzzle political blogs it hosts.

"There's a rumor floating around that the attack may have been politically motivated, but right now I haven't seen the proof to back up that claim," says Roel Schouwenberg, a researcher at Kaspersky Labs. "Currently, we don't have any detailed information as to who may be behind the DDoS."