Vanilla vs. Beta Hunter Pet AI

Can anyone shed light on how Hunter Pet AI works in Beta, vs. how it worked in Vanilla? I'm currently playing hunter on a P server, and Defensive does not work how I remember it. So I want to check my memory against my current experience, and also get an idea of what to expect going forward.

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1. A pet on Defensive should attack if you or the pet take damage. In the server I'm on, your pet will attack if an NPC attempts a melee swing. This means a miss and your pet still attacks, and it also means your pet does not go after casters. In Beta, do pets properly engage when taking damage?
2. I remember that if you have 2+ mobs attacking you or your pet, after the one your pet is on dies, it would go to the next mob. On the server I'm on, it returns unless you manually target the next mob. Am I remembering correctly, or did pets return in Vanilla? How does this work in Beta?
3. If I have my pet on defensive and want it to return to me by hitting "Follow" (Ctrl+2), at what point will the pet re-engage an enemy that attacks it? How did this work in Vanilla vs. Beta?

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Thanks!