IPv6 addresses are 128-bit identifiers for interfaces and sets of interfaces (RFC 4291). In its full notation, an IPv6 address is represented in eight groups of four hexadecimal digits (eight 16-bit blocks) separated by colons (:), for example 2001:0db8:0a0b:12f0:0000:0000:0000:0001

# learn
```bash
nslookup -type=AAAA www.csair.com 2400:3200:0000:0000:0000:0000:0000:0001
ping6 -c5 ipv6.baidu.com
```
# ref
* https://www.gestioip.net/docu/ipv6_address_examples.html
* https://ivanzz1001.github.io/records/post/tcpip/2018/04/22/tcpip_ipv6_address