WASHINGTON — How fast is the Internet growing? A Reston company is keeping track.

Reston-based VeriSign Inc., which registers “.com” and “.net” domains, says a total of 15 million domain names were added to the Internet in the fourth quarter of 2015. That brings the total number of registered domains worldwide to 314 million.

Worldwide registrations grew by 25.9 million in 2015, or an annual rate of about 9 percent last year.

VeriSign says the “.com” and “.net” top level domains reached 139.8 million, for year-over-year growth of 6.3 percent.

The “.com” domains account for about 124 million of those, and “.net” domains total 15.8 million. VeriSign says it processed 12.2 million new domain registrations for “.com” and “.net” in the fourth quarter.

VeriSign also offers a glimpse of just how much worldwide surfing is happening.

During the final three months of 2015, VeriSign’s average daily Domain Name System (DNS) query load was approximately 123 billion queries per day across all top level domains operated by the firm. The one-day peak in the fourth quarter was nearly 194 billion queries.

The peak daily query load was up by 32.6 percent from a year ago.