A built-in data tables on mysql problem

mysql> select host, user from user;
+ ----------- + ------ +
| host | user |
+ ----------- + ------ +
| 127.0.0.1 | root |
| :: 1 | root |
| localhost | root |
+ ----------- + ------ +
3 rows in set (0.00 sec)

user table in a database named mysql

This database is mysql built in the middle I wanted to know what is the meaning of :: 1 ?
------ Solution ---------------------------------------- ----
ipv6 said local address localhost, 127.0.0.1 with ipv4 in the same.
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come ah nobody?
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taught the