It's common that monolithic applications have lots of dependencies on the server where they are deployed. Often, application configuration and code have hardcoded parameters based on server DNS name and IP address. Hardcoded IP configuration creates challenges if you want to bring up a new server in case of an issue with the original server. Additionally, you don't want to bring down the entire application for the upgrade, which may cause significant downtime.
To handle such a situation, you need to create a new server keeping the same server IP address and DNS name. It can be achieved by moving the network interface from a problematic instance to the new server. The network interface is generally a Network Interface Card (NIC), which facilitates communication between servers over a network. It can be in the form of hardware or software. Moving the network interface means that now your new server assumes the identity of the old server. With that...