Hello, I recently purchased a dog from a pet store registered as a jack russell terrier. I have taken him to a puppy training class and the trainer does not trust/believe he is full JRT. I have no clue, I just trusted what the pet store said? Pictures below are from him at 3-months old. Thoughts..?

HI, i bought a beagle puppy like 4 months ago and the puppy is 6 months ,can i please know if my pup is purebred or not as some people say it is not:eyeroll: and as beagles howl , ive never heard my dog howl so i wanna know if its purbred or not:):)