A newly deployed Red Hat Enterprise Linux 7 on Azure will not trust Lets Encrypt TLS certificates.
wget to access a site with a Lets Encrypt certificate, produces this error:
ERROR: cannot verify example.com's certificate, issued by ‘/C=US/O=Let's Encrypt/CN=R3’: Issued certificate has expired. To connect to example.com insecurely, use `--no-check-certificate'.
This is fixed by running this command:
sudo update-ca-trust extract