How can they claim 99.999% uptime, when they just had several hours of service outage? I'm not sure how long they've been providing DNS hosting, but by the most generous assumption this would be the entire 15 years of their existence. 99.999% allows them about 1.3 hours of outage in 15 years.
I don't believe they have a 99.999% SLA. That was their historical up-time.
I just misread their statement. They probably meant the up-time before this incident.
"Throughout our history, we have provided 99.999% uptime in our DNS infrastructure. This is the level our customers expect from us and the level we expect of ourselves. We have let our customers down and we know it."