Apache - How can I limit access only to specific URLs?

[Vitaly Karasik_1]

I have a website (virtual server) and many DNS
aliases pointed to the same server.

But I have some directory which should be accessible
only via specific DNS alias (== URL).
If/How this can be done?

E.g, I have a.example.com, b.example.com,
c.example.com pointed to the same virtualhost.
And for a.example.com I'd like to provide access to
some dir as http://a.example.com/only_for_a.
(it shouldn't be accessible as
http://b.example.com/only_for_a)

[Vitaly Karasik_1]

solved using apache variables:

SetEnvIf Host linux1.example.com allow_host_linux1


Order Deny,Allow
Deny from all
Allow from env=allow_host_linux1

[Ivan Ferreira]

Please correct me if I'm wrong, but if you specify a different DocumentRoot for each virtual host, and for example, a different directory includes in each virtual host:

Include conf.d//*.conf

The pages available to one virtual host sould not be served by another virtual host.

[Vitaly Karasik_1]

Ivan, thank you!
In my configuration I use just DNS aliases for different customers, I don't have apache virtualhost per customer.