I tried to put the line to /etc/hosts:

> 
> IP math.com mathworld.com
> 
> 
> 

where IP was supposed to be the IP of <http://mathworld.wolfram.com/classroom/>. I pinged the site, and I realised that I must direct traffic with some other tools:

> 
> ping mathworld.wolfram.com/
> 
> 
> ping: cannot resolve mathworld.wolfram.com/: Unknown host
> 
> 
> 

So the question arises:

> 
> How can I direct traffic to subdomains, similar to the above subdomain?
> 
> 
>