a::b
a::b2
a::b testing
http://[a::b]:80 testing
a::b2 testing2
000a::000b
b::c
b::c2
a:0:0:0:0:0:0:b
2001:db8:0:0:1:0:0:1
2001:0db8:0:0:1:0:0:1
2001:db8::1:0:0:1
2001:db8::0:1:0:0:1
2001:0db8::1:0:0:1
2001:db8:0:0:1::1
2001:db8:0000:0:1::1
2001:DB8:0:0:1::1