If I have registered multiple domain names but only intend to use one domain name for the website in question and put 301 redirects in place for all of the others, do I only need assign one domain name to an IP address?
I think what he is asking is this: 'I purchased multiple domain names. I intend to use ONE of them for a website, and have the others redirect to that one. Do I need to buy additional IP addresses for those domains even if they're not going to host anything but rather just redirect to the first domain?'
Important note: You can host 1000 domains (any number of) on one IP address, or one domain on 1000 (any number) of IP addresses. The way we accomplish this is through either 'shared' or 'cloud-based' (being simple here) hosting. You don't need to purchase or use more than one IP address for your domains, even if you are hosting different websites on them. Even doing the redirects, you'd only need one IP address (physically).
To accomplish the redirect from your old domains, simply put this in a
If you need additional help, please comment.
All of the domains need to point to the IP address (using A or CNAME records in the DNS), otherwise they will not resolve.
They also need to be handled by the webserver (eg IIS or Apache) so that the webserver knows to process the request (or at least, the IP address configured to catch all requests)
I'm not familiar with the setup for IIS, but the Apache configuration (usually httpd.conf) can include the 301 redirection suggested by @ionFish, or else it needs to be done at the site .htaccess file