A lot of times I've seen questions about how this works when you have multiple nodes or a CDN, it can be quite tricky in theory if you have random IPs or several IPs.
The way certbot works at least for non-DNS challenges is that it will hit a random server that it resolves to, you have no control over which one it hits.
If certbot hits node 1 at first to tell it to create the well-known file, then checks node 2 or any other node, you will find auhorization fails.........
For some reason, perhaps you don't want to run a daemon or let Letsencrypt have access to your production server.
There is a way to use it like a normal CSR/CA setup in manual mode.
./letsencrypt-auto certonly --manual -d realtechtalk.com - www.realtechtalk.com
Eventually you will get prompted to create a certain path and file with certain data:
Create a file containing just this data:
Casdfasfadsfsad........
./certbot-auto --apache certonly
Saving debug log to /var/log/letsencrypt/letsencrypt.log
Plugins selected: Authenticator apache, Installer apache
No names were found in your configuration files. Please enter in your domain
name(s) (comma and/or space separated) (Enter 'c' to cancel): yourdomain.com
Obtaining a new certificate
Performing the following challenges:
http-01 challenge for yourdomain.com
Cleaning........