I know a fair amount about DNS, and I'd say that what UltraDNS is claiming is largely crap.
Now... if you're GAP or Amazon or somebody that has an insane amount of traffic (literally enough to overload DNS requests), then *maybe* you'd see a marginal increase... but even that seems pretty shaky.
You have to realize that DNS is a distributed architecture; when Bob Potatohead who has Comcast types in yourdomain.com, Bob's computer asks Comcast's DNS where your site is located (which IP address.) ONLY if no one else on Comcast has asked for your site (sent an email to you or loaded the webpage) will Comcast's DNS even ask your DNS for info; otherwise the info is held in Comcast's DNS until it expires or they dump their cache. And it's the same with every other ISP.
So.. that being the case, UltraDNS is only responding to requests coming from ISPs that your surfers are using, not from any individual surfers. Given that the majority of adult surfers are using broadband, they tend to be using large ISPs with their own large DNS networks, who will have already cached your information from the first request. Therefore, no hit to UltraDNS, no "increase in speed."
Given that minimal level of traffic, the likelihood that whatever DNS your web host runs is going to get clobbered or overrun enough to actually lose traffic is near zero. THAT, IN FACT, IS WHY TWO DNS SERVERS ARE REQUIRED; in case one is busy, slow, offline, or otherwise unavailable, traffic automatically fails over to the other server(s). Many ISPs and even domain registrars now offer 5 or 6 DNS servers free; Enom, for example, provides redundant service on 5 DNS servers, geographically spread. So does ZoneEdit. Enom's DNS is free with domain registration services; ZoneEdit's costs about $5/YEAR!!
Oh... and UltraDNS's argument that their proprietary DNS is so much better than BIND? Hogwash. BIND may be old, but about 90% of the 'Net runs on it, has for years. It's solid, reliable, does its job quite well. If you *really* don't want to use BIND, there are several alternate DNS servers out there you can buy for fairly cheap.
So... I hope you can see that, absent the folks with insanely large amounts of traffic (and, perhaps, even for them) there's very little reason to believe that switching to somebody's whiz-bang DNS is going to have any effect on your traffic.
Unless a team of offshore people clicking to your site to artificially boost stats is included for free with an UltraDNS account
