Is the IPv6 case sensitive

Question

Are the IPv6 addresses case sensitive ?

2001:0:5ef5:79fb:b5:9ca5:a266:e068

vs

2001:0:5EF5:79FB:B5:9CA5:A266:E068

I'm guessing they are both correct but I need to be sure.

Answer 1

Technically, an IPv6 address is case-insensitive, but RFC 5952, A Recommendation for IPv6 Address Text Representation, Section 4.3 Lowercase says:

The characters "a", "b", "c", "d", "e", and "f" in an IPv6 address
MUST be represented in lowercase.