It can be anything! An apex, subdomain, or even a URL.

Results fornand.vanitydomains.qualtrics.com

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2020-09-17T05:50:43.427	2020-09-17T04:50:42	2020-12-16T04:50:42	nand.vanitydomains.qualtrics.com	nand.vanitydomains.qualtrics.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-09-17T05:50:43.092	2020-09-17T04:50:42	2020-12-16T04:50:42	nand.vanitydomains.qualtrics.com	nand.vanitydomains.qualtrics.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-09-16T23:09:57.958	2020-09-16T22:09:57	2020-12-15T22:09:57	nand.vanitydomains.qualtrics.com	nand.vanitydomains.qualtrics.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-09-16T23:09:57.76	2020-09-16T22:09:57	2020-12-15T22:09:57	nand.vanitydomains.qualtrics.com	nand.vanitydomains.qualtrics.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3