I also had the care home and Dr asking very early on - if you don't have LPA they are probably trying to get the answer from him ASAP in case capacity is judged to be lost. If you can help get that subject broached with him, all the better, as far as they are concerned. I don't think it means anything like end of life is near or something else, it seems to be an admin exercise.
Now, if they'd asked me in your place with my dad, I would have said DNR/DNAR immediately - as
@nitram rightly points out, it's very invasive, and recovery is very hard, painful, and long, assuming it would even work. And indeed I believe that the Dad I knew would have felt this way. My best friend's dad was a successful resus when I was a teenager and he was very poorly for a long time afterwards.
However, on the day a Dr visited Dad he was having a pretty jolly day and seemed quite together, so his capacity was judged to be intact, so they posed the question to Dad and he insisted that he be resuscitated. So that is on his medical notes - ATTEMPT RESUS.
Dad often talks about his life after the care home, and in his mind he's still a young man so of course, he wouldn't agree to DNR. What will be will be I suppose.
With that said, don't feel too pressured to agree to DNR if you don't feel strongly about it -I am having to trust that when it's truly his time, Dad will go.