ubuntu 16.04执行apt-get update失败卡住的解决方法

luder@ubuntu:~$ sudo apt update
0% [Connecting to us.archive.ubuntu.com (2001:67c:1562::19)] [Connecting to sec^C

打开/etc/gai.conf

找到

#precedence ::ffff:0:0/96  100

把前面的"#"去掉即可。

# precedence  <mask>   <value>
#    Add another rule to the RFC 3484 precedence table.  See section 2.1
#    and 10.3 in RFC 3484.  The default is:
#
#precedence  ::1/128       50
#precedence  ::/0          40
#precedence  2002::/16     30
#precedence ::/96          20
#precedence ::ffff:0:0/96  10
#
#    For sites which prefer IPv4 connections change the last line to
#
precedence ::ffff:0:0/96  100

#
# scopev4  <mask>  <value>

再次执行  apt-get update 就没有问题了。