How is IPNS data stored in the network?

This is a question I couldn’t find an answer to via search engine. For my own technical knowledge, I’d like to understand how IPNS domains are stored across the network. Does IPFS use a blockchain for that, or a database distributed across the network and seeded by every node, or is there another approach?

One of my concerns is: When it comes to files, data can disappear from the IPFS network when a file runs out of peers to seed it. I’d like to know how IPFS stores and updates IPNS entries to understand whether the same risk exists here, and those entries also need to be pinned in order to assure their availability.