Create cert for Exchange

Good afternoon!
I want to create a certificate for Exchange
I am running wass.exe as administrator
I select the type of verification - [http-01] Serve verification files from memory
But when validation is run I get an error: invalid response from

Right now I'm using office365
On the external DNS, I have a CNAME entry for autodiscover

Do I need to make a type A record on the external dns for my exchange server?

Hi @pgb, and welcome to the LE community forum :slight_smile:

Notice the IPv6 address in the request:
Be sure that your website works for IPv6 and IPv4.

Furthermore, without a real domain name, there isn't much more anyone here can do to troubleshoot this problem.