Popular link-shortening service is.gd has experienced a prolonged denial-of-service attack (DoS) that has resulted in a majority of its shortened URLs to go down.

The service was initially unavailable on Sunday, causing the site's hosting provider to temporarily suspend access in order to mitigate the effect of the attack on the network, according to a blost post on the service's site.

Netcraft, a UK-based security service provider, indicated that more than a billion of the shortened URL's may have been affected, and that those links were accessed “nearly 50 billion times.”

An updated blog post by site administrators indicates that is.gd has implemented a third-party DoS protection service, but ran into issues when attempting to gain administrative control of its domain to alter its configuration, thus prolonging the service's outage.

As of this report, the site and service is once again active.