There is a lot of confusion in the answers I fount about it.

When I installed nginx first, it was the debian jessie version 1.6.2 and the configuration to listen to both ipv4 and ipv6 was

#server {
# listen 80;
# listen [::]:80;
#
# server_name example.com;
#
# root /var/www/example.com;
# index index.html;
#
# location / {
# try_files $uri $uri/ =404;
# }
#}

Now I use nginx 1.11.10 and the example configuration file only has one line:
listen 80;


Should I update my configuration? I might be wrong but I did not see ipv6 requests for a long while.

Last time I changed the listen directive following some recommendation found on the web, I ended up with servers not listening to anything!