Domain name parking service NameDrive restored its services on Friday after coming under a concerted and ferocious denial of service attack from unidentified hackers.

The motives for the attack remain unclear but NameDrive reckons crackers expanded vast resources to flood its website with spurious traffic.

NameDrive offers a service that allows domain owners to "park" inactive domains. Targeted ads are placed on these parked domains, enabling owners to rake in a percentage whenever visitors to the domains click on the ads. These services have now been restored while the firm works on restoring its home page.

The firm is reassuring customers that their commission would not be affected by the attack. NameDrive said it has defences in place to combat denial of service attacks. The ferocity of the latest attack took it by surprise, however.

"We deal with a DDOS pretty much every day, but even our sophisticated defenses our somewhat overwhelmed by this," a posting on its blog states.

The attack started Thursday at around 15.00 GMT and remains ongoing, a later post explains. "In addition to the 600K domains we have parked on our system, our servers were being hit by XX,XXX false connections per second for over 24 hours. The attack is increasing as we speak and has been since it began.

"We estimate that just to keep up this attack, it has cost the aggressor at least five figures and possibly six figures to initiate and sustain. This wasn't poor defenses on our part, it was the use of overwhelming force and financial resources on theirs," it adds.

Around 100 domains parked at NameDrive were recently linked to a spam Trojan campaign. NameDrive said the denial of service attack was unrelated to this assault. ®