[root@prague conf.d]# certbot certonly --manual -d prague.acim.cz --preferred-challenges="dns"
Saving debug log to /var/log/letsencrypt/letsencrypt.log
Plugins selected: Authenticator manual, Installer None
Starting new HTTPS connection (1): acme-v01.api.letsencrypt.org
Cert not yet due for renewal
 
You have an existing certificate that has exactly the same domains or certificate name you requested and isn't close to expiry.
(ref: /etc/letsencrypt/renewal/prague.acim.cz.conf)
 
What would you like to do?
-------------------------------------------------------------------------------
1: Keep the existing certificate for now
2: Renew & replace the cert (limit ~5 per 7 days)
-------------------------------------------------------------------------------
Select the appropriate number [1-2] then [enter] (press 'c' to cancel): 2
Renewing an existing certificate
Performing the following challenges:
dns-01 challenge for prague.acim.cz
 
-------------------------------------------------------------------------------
NOTE: The IP of this machine will be publicly logged as having requested this
certificate. If you're running certbot in manual mode on a machine that is not
your server, please ensure you're okay with that.
 
Are you OK with your IP being logged?
-------------------------------------------------------------------------------
(Y)es/(N)o: y
 
-------------------------------------------------------------------------------
Please deploy a DNS TXT record under the name
_acme-challenge.prague.acim.cz with the following value:
 
TA_U12HOMamwt8e5qLy8H9s6LRWP-O0Ap3TzVkAiVus
 
Before continuing, verify the record is deployed.
-------------------------------------------------------------------------------
Press Enter to Continue
Waiting for verification...
Cleaning up challenges
 
IMPORTANT NOTES:
 - Congratulations! Your certificate and chain have been saved at:
   /etc/letsencrypt/live/prague.acim.cz/fullchain.pem
   Your key file has been saved at:
   /etc/letsencrypt/live/prague.acim.cz/privkey.pem
   Your cert will expire on 2018-08-07. To obtain a new or tweaked
   version of this certificate in the future, simply run certbot
   again. To non-interactively renew *all* of your certificates, run
   "certbot renew"
 - If you like Certbot, please consider supporting our work by:
 
   Donating to ISRG / Let's Encrypt:   https://letsencrypt.org/donate
   Donating to EFF:                    https://eff.org/donate-le
 
[root@prague conf.d]#