In which two ways does the OpenDNS infrastructure ensure reliability? (Choose two)
A. It ensures redundancy by using at least two telecom carriers at each site
B. It uses a self-healing network to protect against individual failures
C. Its networks are geographically integrated to reduce the potential impact of local issues
D. Regional sites load-balance among one another to prevent bottlenecks
E. It uses multicast routing to ensure that requests are routes to the nearest data
F. It uses a specialized form of multicast addressing called Geocast ensure the most efficient routing when a local site goes down
G. It limits caching to reduce the incidence of state and dead links
AB
https://www.opendns.com/about/global-dns-infrastructure/
Why are we so reliable?
We’ve built a self-healing network across three continents to give you the most reliable DNS service on the planet. By self-healing, we mean we’ve designed against the failure of nearly every aspect of our system and can withstand tremendous disruption to our infrastructure without causing disruption for our customers. We use multiple telecom carriers at every site to ensure full redundancy of our Internet bandwidth. We also connect to regional networks at every site to help geographically isolate traffic so that an issue in one region doesn’t spillover and impact another. All of this bandwidth then feeds into a large cluster of servers at each site that is constantly balancing the load across itself.
Our Anycast routing infrastructure not only provides speed, but it also makes us more reliable. By having an IP address spread across our global datacenter locations, we increase the overall resiliency of the system. If one of our datacenters were to go offline due to a natural disaster, equipment failure or maintenance, all requests would be transparently re-routed to the next closest location. At all times we maintain at least 50 percent capacity, and often much more than that in order to handle massive traffic spikes.