You should only use 4.2.2.1 or 4.2.2.2 if you're an actual Level3 customer. While they do respond to public requests, they're not intended for public use, unlike Google's 8.8.8.8 and 8.8.4.4 servers.
Interesting. I seen to remember that at one point the reverse lookup for one of the 4.2.2.x addresses was "dont-steal-service-etc.somebody". I just send an ICMP ping when I need an IP to check a connection. I also seem to recall reading that the 4.2.2.x resolvers were multi-homed, but in both cases my memory could be faulty.
You should only use 4.2.2.1 or 4.2.2.2 if you're an actual Level3 customer. While they do respond to public requests, they're not intended for public use, unlike Google's 8.8.8.8 and 8.8.4.4 servers.
https://news.ycombinator.com/item?id=7120248
Level3's VP says they're public.
(They go up to 4.2.2.6 too, I think.)
Interesting. I seen to remember that at one point the reverse lookup for one of the 4.2.2.x addresses was "dont-steal-service-etc.somebody". I just send an ICMP ping when I need an IP to check a connection. I also seem to recall reading that the 4.2.2.x resolvers were multi-homed, but in both cases my memory could be faulty.
Or google's at 8.8.8.8 and 8.8.4.4 ?