I'm not really sure if this is something that I should worry about... I'm currently renting a dedicated server which is hosting a website I've created. The domain of the website was registered with GoDaddy. After submitting a sitemap to Google several months ago, I've noticed that another domain name is resolving to my IP address. This means that every page on my website is actually accessible from another domain. As far as I can tell, the other domain name is meaningless to me, so I'm not sure if this is something I should worry about or not. Is this a residual DNS record from another site that is probably no longer in use? Is it important from the standpoint of either security or SEO? My website is a .com which will later serve e-commerce purposes. The other domain has a top-level domain of st. It's the first one of those that I've encountered.

Many thanks in advance!