<link rel="icon" href="icon.gif" />

<link rel="shortcut icon" href="favicon.ico" />
                                   -----^-----
             <!--Remember to have .ico as the extension else
                 some browsers fail to load other extensions -->

<link rel="icon" href="icon.gif" />

Options +FollowSymLinks -MultiViews
<IfModule mod_rewrite.c>
    RewriteEngine On
    RewriteRule ^(favicon.ico)$ %{HTTP_HOST}/$1 [L,NC]
</IfModule>

<link rel="shortcut icon" href="favicon.ico">
<link rel="icon" type="image/gif" href="animated_favicon1.gif">