Hi All,

Salesforce IP Range and Domain Whitelisting

During an integration with a 3rd party system, I have come across the issue, "Whitelisting the Salesforce IP Ranges and Domains". 
Salesforce knowledge article says and listed out several IP Ranges (eg: 182.50.78.5 - 182.50.78.15 - one of the APNIC range) to be whitelisted.

Here is my question, if the given(by Salesforce) IP's( 182.50.78.5 - 182.50.78.15 ) are whitelisted, all the organisation(Salesforce Org) lies in AP(Salesforce Asia Pacific Server) and whichever the organisation(Salesforce Org) using the same IP range to communicate with other system can have the access to our Server as well.
Hence, there is loophole and our Server firewall is exposed for all Salesforce Org's. This will not actually work not a right approach. 

We have to make sure that the request is coming from a authorized Salesforce Org. Is there anything we can get like a specific IP for one Salesforce Organisation? Something like this is necessary to make the Integration successful.
Please suggest me a good solution. 

Is it possible to whitelist the Custom Doimain Name "<mydomain>.my.salesforce.com"?

Regards,
Saravana.