No, it's not random. There are some loose gear checks and gear matching systems in place. The Dungeon Finder weights dungeons you've already run a little lower, but then also looks at who is in the queue, what they are in the queue for, and tries to figure out the quickest way to get you inside a dungeon. It's a fairly complicated algorithm that isn't trivial, took a good deal of time to develop, and we're happy with the way it's turned out. Ultimately, it's getting players in dungeons with minimal wait times, but it's not completely random.
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