I am an absolute noob in web development, but I have a Wordpress site and while I was trying to verify my website for Youtube, I made a mistake and changed 2 CNAME entries on my 1und1.de (german version of 1and1.com) webhosting page under "DNS settings".
These CNAME entries were titled "autodiscover" and "_domainconnect" but I forgot their original value. I contacted the 1and1 support, but the guy on the other side didn't really have a clue and said that I should know what these entries are (even though I didn't add them, they were there by default).
The phone call lead to no solution but he implied that I could delete them, and so I did. I deleted these entries and my page is still working, but I don't know if I did any damage under the hood.