Please fill out the fields below so we can help you better. Note: you must provide your domain name to get help. Domain names for issued certificates are all made public in Certificate Transparency logs (e.g. https://crt.sh/?q=example.com), so withholding your domain name here does not increase secrecy, but only makes it harder for us to provide help.
I ran this command: sudo ./certbot-auto --apache --agree-tos --rsa-key-size 4096 --email user@domain.org --redirect -d nc.domain.org
My web server is (include version): Apache 2.4
The operating system my web server runs on is (include version): Ubuntu 16.04
It produced this output:
Saving debug log to /var/log/letsencrypt/letsencrypt.log
Plugins selected: Authenticator apache, Installer apache
Obtaining a new certificate
Performing the following challenges:
http-01 challenge for cloud03.lstmed.ac.uk
Waiting for verification…
Cleaning up challenges
Failed authorization procedure. cloud03.lstmed.ac.uk (http-01): urn:ietf:params:acme:error:dns :: DNS problem: NXDOMAIN looking up A for cloud03.lstmed.ac.uk
To fix these errors, please make sure that your domain name was
entered correctly and the DNS A/AAAA record(s) for that domain
contain(s) the right IP address. Additionally, please check that
your computer has a publicly routable IP address and that no
firewalls are preventing the server from communicating with the
client. If you’re using the webroot plugin, you should also verify
that you are serving files from the webroot path you provided.
Can anyone help with a guide on how to do this? Please bear in mind I’m relatively new to Linux (Base server builds are fine, SSL certificates always tend to fail with me though)
Any such guide would have to be based on all the details of your configuration, thus no such guide is possible. Something is blocking connections to port 80 from the Internet at large. Until you resolve that, you won't be able to get a cert using the HTTP validator. If that something happens to be your ISP (as isn't unusual for residential ISPs, for example), you may be out of luck.