Apache2 ServerName and ServerAlias not working

On a nearly fresh Ubuntu 20.04 LTS computer, I would like to set up a virtual host on my local machine. So I created a index.html under /var/www/test/ with the following content:
you have entered a test page

I have set up a test.conf file under /etc/apache2/sites-available/

with the following content:

<VirtualHost *:80>
    ServerAdmin [email protected]
    DocumentRoot /var/www/test/
    ServerName zhihu.com
    ServerAlias www.zhihu.com
    <Directory /var/www/test/>
        Options Indexes FollowSymLinks
        AllowOverride All 
        Require all granted     
    </Directory>
    ErrorLog ${APACHE_LOG_DIR}/error.log
    CustomLog ${APACHE_LOG_DIR}/access.log combined
</VirtualHost>

The localhost is working:

/etc/hosts config is probably working as indicated by ping

ping zhihu.com
PING zhihu.com (127.0.1.1) 56(84) bytes of data.
64 bytes from xxx (127.0.1.1): icmp_seq=1 ttl=64 time=0.045 ms

but browser cannot bring me to the domain which should now be hosted in /var/www/test/.

I have also a2ensite test.conf and a2dissite 000-default.conf and service apache2 reload

So I think the only possible place for error to occur is ServerName and ServerAlias. Why are they not working?