If you’re up for some light reading: http://www.tummy.com/Community/Articles/famous-dns-server/
If you’re not the “reading type,” here’s the key part of the article: Should I Use 22.214.171.124? Unless you are a Level-3 customer, absolutely not.
Essentially, 126.96.36.199 belongs to Level 3, and they have no obligation to ensure that this service is reliable or accurate. As of late, a number of DNS queries made against 188.8.131.52 have been timing out, which makes it a bad choice to verify DNS name resolution.
184.108.40.206 and 220.127.116.11, please.
To add to this, Allied Telecom (and my independent tests) have noted that 18.104.22.168 is having some major issues today, which is manifesting itself as many of their customers calling them for Internet connectivity issues when the issue actually lies with the DNS provider that the IT Engineer chose to put in the firewall/DNS settings long before 22.214.171.124 started going downhill.