Runs a DNS lookup 5 times, and averages out the time.
$ go run main.go testdomain.com
2019/09/21 14:11:08 Google - 8.8.8.8 avg 22.801956ms
2019/09/21 14:11:08 Google2 - 8.8.4.4 avg 20.767106ms
2019/09/21 14:11:08 CloudFlare - 1.1.1.1 avg 19.154577ms
2019/09/21 14:11:08 Quad 9s - 9.9.9.9 avg 53.829064ms
2019/09/21 14:11:08 OpenDNS - 208.67.222.222 avg 26.413981ms
2019/09/21 14:11:08 OpenDNS2 - 208.67.222.220 avg 20.318214ms
2019/09/21 14:11:08 DNS Advantage - 156.154.70.1 avg 65.551849ms