Information
This setting determines whether Internationalized Domain Names (IDNs) displayed in the browser are displayed as Punycode or as Unicode.
Rationale:
IDNs displayed in Punycode are easier to identify and therefore help mitigate the risk of accessing spoofed web pages.
Solution
To establish the recommended configuration, set network.IDN_show_punycode to true:
Type about:config in the address bar
Type network.IDN_show_punycode in the filter
Configure the setting as prescribed.
OR
Open the mozilla.cfg file in the installation directory with a text editor
Add the following lines to mozilla.cfg:
lockPref('network.IDN_show_punycode', true);
Default Value:
False