Back when I was onboarding customers, I use to have these tools at my fingertips. Recently, I added a new domain to my portfolio https://billhertz.ing and in the process of building, I needed these tools once again.

Redirect Checker

https://www.whatsmydns.net/redirect-checker - You will use this to see how your links are redirecting to another domain. You might see codes like "301 Moved Permanently" which is good. You might also see "403 Forbidden".

DNS Propogation Checker

https://www.whatsmydns.net/ - When you make a change to your DNS, you will want to see if the changes have taken place around the globe. This is the tool to use.