Kerberos is a network authentication protocol that uses tickets to allow clients and servers to prove their identity to each other. Kerberos relies on accurate time synchronization between the parties involved, as the tickets have expiration dates and timestamps. If the system clock of a Linux server is off by more than five minutes from the LDAP server or the domain controller, the Kerberos authentication will fail and generate errors. A local firewall is unlikely to block authentication requests if the server can communicate over the network and is configured correctly. The users' passwords are not relevant if they are known-working LDAP credentials. The server has access to the LDAP host if it can communicate over the network and is configured correctly. References:
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html/identity_management_gui
https://www.ibm.com/docs/en/aix/7.2?topic=authentication-kerberos-time-synchronization

This is the most likely cause of the issue because firewall rules can block or allow traffic based on source, destination, port, protocol, or other criteria. If the firewall rules are not configured properly, they can prevent remote users from accessing the cloud application server, while allowing on-site users to access it. References:
https://docs.microsoft.com/en-us/azure/virtual-network/security-overview

The administrator needs to install SSL to make the website trusted. SSL stands for Secure Sockets Layer, which is an encryption-based Internet security protocol that ensures privacy, authentication, and data integrity in web communications. SSL enables HTTPS (Hypertext Transfer Protocol Secure), which is a secure version of HTTP (Hypertext Transfer Protocol) that encrypts the data exchanged between a web browser and a web server. SSL also uses digital certificates to verify the identity of the web server and establish trust with the web browser. A web server that implements SSL has HTTPS in its URL instead of HTTP and displays a padlock icon or a green bar in the browser's address bar.

This is the best command to find out which commands can be used by a user with sudo privileges because it lists the allowed and forbidden commands for a given user or role. The -l option stands for list, and the -U option specifies the user name. The output of this command will show what commands can be executed with sudo by that user on that server. References: https://www.sudo.ws/man/1.8.13/sudo.man.html

The action that the server administrator should take once a new backup scheme has been configured is to run a restore test. A restore test is a process of verifying that the backup data can be successfully recovered and restored to its original location or a different location. A restore test can help ensure that the backup scheme is working properly, that the backup data is valid and consistent, and that there are no errors or issues during the recovery process. A restore test should be performed periodically and after any changes to the backup configuration or environment.