Ok thanks for your help. If there're more servers like mine, everyone with a different IP but the same router, how's the traffic redirected to the specific server? You can open a port and do a selective redirect basing on IP?

If there are more physical servers sharing the same router, the router will have to send everything coming to port 80 to a redirecting server. It inspects the HTTP header of the incoming packet, extracts the name and with that information can do the redirection to the appropiate server.

Thanks. What do you think about this solution? I'd good for a public domain name, consisting Google for example?

Depends of the expected incoming traffic. Google needs to use very sophisticated systems to ensure quick response and high availability. I know that a simple server using apachecan do the task of redirecting server, but in a high traffic situation it can be a bottle neck. Read about virtual hostingto learn how hosting providers do this.

I've executed wget http://ipecho.net/plain -O - -q ; echo and it gave me a different result from viewdns. How can this be possible?

Then, the domain name is not associated with your actual public IP and it is going to any other place, From the centOS server do a traceroute to the IP result of ViewDNS. It could give you a clue.

It gave me 30 "* * *". If I visit example.com/test.html, I see the "test.html" file I'm working on this server.

Hello, thank you so much for your patience jcbermu

What happens when you do a x.x.x.x where x.x.x.x is an IP address? First use the public IP you found using ipcho.net and the the IP you found through dnsinfo

I'm testing it.

The IP I got from wget sends me to mysite.com

nope, excuse me

the IP I got from viewDNS sends me to mysite.com

the IP I got from wget returns a blank page

Has the CentOS server more than one interface?

From ip addr it returned two interfaces.

1: lo: <LOOPBACK,UP,LOWER_UP>

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP>

Are the two IPs on a close range or are they very different?

close range. Only the last part is different

OK.

x.x.x.Y where Y is the only different part

The connection to your Internet Ptovider has two IP addresses. One of them is used for incoming and the other one for outgoing

the ipecho.net test the outgoing IP, meanwhile DNSInfo tests the incoming

Ok

Simply your ISP (Internet Provider) has provided you with two IPs

Thanks, I've to do some works on this servers and if I don't understand the structure of the server perfectly then I can't do many things!

And one of them has been correlated to the domain name and the port 80 on the router.

Thank you so much once again for your infinite patience

The other one is been used only as outgoing, so any outside request gets to nowhere (the blank page).

Is this a common thing?

It's the first time I'm working on a private envirnoment, actually I'm studying on servers from a society which hosts all servers

Ok, thanks again, really appreciate your support! :) Have a nice week-end :)

It's more common in a place that hosts multiple services / servers and additional IPs gives them easy management of incoming traffic.

You're welcome