At the US University of Kansas, social-networking sites, including MySpace, Facebook and YouTube, are among the 10 most popular destinations for a user population that averages 20,000 per day, including faculty, staff and students.
These sites "generate a lot of DNS requests since each item on the Web pages is spread over dozens and dozens of servers", says Travis Berkley, supervisor of LAN support services at the university.
The school hasn't needed to upgrade its DNS infrastructure yet to handle the extra traffic that social-networking sites generate. It runs BIND Version 9 software for its DNS servers.
"We have two servers that are the primary for campus, and they seem to keep up just fine," Berkley says, adding that "some departments have set up their own workgroup DNS servers".
One advantage for the university is that it already limits how much Internet bandwidth students can consume from their dorm rooms. So even though the university doesn't limit access to social-networking sites, it can ensure that usage of these sites is limited to a fixed proportion of its Internet bandwidth.
"We did that independent of these sites or even peer-to-peer," Berkley added.
MySpace seems to be the biggest contributor of the social-networking sites in terms of fostering DNS queries. MySpace declined to comment for this article.
"MySpace is really a pain in the butt," says Cricket Liu, vice president of architecture at US-based InfoBlox, which sells DNS appliances to carriers and corporations. "It generates an enormous number of DNS queries because of the way it refers to content. The domain names they are using all seem to be part of their own content-delivery network."
Liu says any organization running a recursive name server will feel the pinch from MySpace's DNS-heavy design. That includes carriers, universities and corporations.
"The recursive name server is ultimately responsible for getting the answer on behalf of the resolver on the laptop or desktop machine," Liu explains. "So it's the one that has to go out and navigate the Internet's name space, find the authoritative name server for MySpace.com and get the data back. Then it has to keep going back to the MySpace.com name servers to resolve the different domain names on a page. ... It might have to hit those MySpace.com name servers 45 times or more for a particular page."
MySpace's own DNS servers are less affected by this situation than those run by carriers or enterprises.
"The amount of horsepower it takes to handle a recursive query is more than it takes to handle an authoritative query," Liu explains. "MySpace has to run name servers that are authoritative for MySpace.com. ... The same piece of hardware can do an order of magnitude more responses when it's authoritative for MySpace.com than it can do acting as a recursive server. That's because it doesn't have to track the ongoing progress of the name resolution process; it just has to answer it."
The impact of sites like MySpace is also minor on the root servers and top-level domains. For example, VeriSign estimates that social-networking sites account for less than 1 percent of the DNS queries at the .com and .net level. VeriSign handles 32 billion DNS queries a day.
Experts agree that carriers and enterprises are the ones that will need to watch their DNS traffic trends in light of the "MySpace Effect".
"The rise of social-networking sites is just one of a number of factors that are causing the increase in DNS queries," Liu says. "Another would be antispam mechanisms and just the increasing penetration of broadband."
And it's not just DNS queries that social-networking sites like MySpace drive, but also large volumes of traffic.
"Social-media sites are driving a fantastic amount of usage," Akamai's Afergan says. "These sites are motivating their users to be interacting with their sites in a very engaging way, which is driving a large experience time."
Afergan says social-networking sites affect network utilization in two ways: the profile-based sites like MySpace generate a lot of requests per user for small files, while the video-based sites like YouTube demand a lot of bandwidth for large video files to be transmitted across the network.
"Most of our networking partners are seeing these sites drive an incredible amount of traffic, both in the number of requests and the bytes involved in those requests," says Afergan.
The heavy network demand of these Web sites is one reason that seven of the top 10 social-networking sites use Akamai's content-delivery service to offload traffic. It's also a reason that many carriers allow Akamai to put edge servers inside their networks to serve up rich content locally.
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