I need to understand what methodology Splunk applies in order to update. This is to allow updates through a Firewall. I need to understand what ports and URLs/Addresses to allow our instance to connect with externally, to allow update services such as security patches.
For further information of how to update your environment, refer to the docs (according to your version) here. Be sure to follow the docs that are meant for your environment - standalone server, distributed, indexer cluster or indexer cluster with search head cluster.