The problem is even after you published your site in your local IIS, your computer still doesn't know the IP address corresponding to name "dev.sampleproject.com". Your browser tries to resolve the name, but DNS server obviously knows nothing about it, and there's no local source of this information.
In order to make your site availabe to anyone who knows just its name you need to register your site with DNS server, so that when someone attempts to reach "dev.sampleproject.com" this name gets resolved in your IP address.
But, as I suspect, you only want to test your site in your local environment. This is quite simple to achieve: Windows has a file named "hosts", located at
directory, that contains pairs "IP address - symbolic name". These records are also used by OS to resolve symbolic resource name to an IP address (as far as I know, it is checked even before request to DNS server). So, if you want all your requests to dev.sampleproject.com to be sent to your own machine, open this file and add new record:
[your IP] dev.sampleproject.com
, for example: