The DDoS attacks that flooded Dyn last month and knocked some high-profile Web sites offline don\u2019t mean businesses should abandon it or other DNS service providers, Gartner says.In fact, the best way to go is to make sure critical Web sites are backed by more than one DNS provider, says Gartner analyst Bob Gill.+More on Network World: Gartner Top 10 technology trends you should know for 2017+It\u2019s also the easiest way for an enterprise to defend against this type of attack and the only one known to be effective. \u201cThere\u2019s nothing more elegant anyone has come up with in the intervening week,\u201d he says.The high-volume, high-velocity attack was based largely on a botnet backed by Mirai malware that finds and infects internet of things devices that are virtually defenseless against it. It has proven capable of DDoS traffic of 1Tbps or more and the source code has been made public, so experts say it\u2019s certain there will be more such attacks.Before the Dyn attacks, DNS services were considered vastly more reliable in-house DNS, and it still should be, Gill says. \u201cIf an enterprise had been hit with the volume Dyn was they would have been toast,\u201d Gill says.He says he has been briefed by Dyn about the Oct. 21-22 attacks, most of which he can\u2019t discuss publicly. But he says those Dyn customers that recovered quickly were those who dual-sourced their DNS service. \u201cA significant number of Dyn customers popped back up after 10 to 15 minutes,\u201d he says, and likely they were the ones with more than one DNS provider.+More on Network World: Gartner: Artificial intelligence, algorithms and smart software at the heart of big network changes+Downsides of multiple providers is they represent an extra expense and not all providers offer exactly similar features such as telemetry, local-based routing and fault tolerance. So switching from one to another in an emergency might be complicated and might mean winding up with a different set of features. Coordinating multiple providers is an added headache.If cost is a concern, businesses could use a DNS provider like Amazon Web Service\u2019s Route 53 that is inexpensive, relatively easy to set up and pay-as-you-go, he says.Gill says the motivation for the attack is hard to know. Dyn was a very attractive target for many possible reasons. It had advertised its security, and that might have been considered a reason for a glory-seeking attacker to go after it and take it down.A Dyn researcher delivered a paper on the links between DDoS mitigation firms and DDoS attacks the day before Dyn was hit, so perhaps the attack was revenge. Dyn has many high-profile customers, so perhaps the real target was one of them. It\u2019s impossible to know for sure what the motive was.Gill says Dyn has learned a great deal about how to successfully mitigate this new class of attack. In general, after such incidents, providers ally themselves with other providers to help identify and block malicious traffic at the edges between their networks. Attacks may result in identifying new profiles of attack traffic that make it easier to sort out bad from good in future incidents.