Where docker checks for the image availability on the docker host

Hi,
In the Docker documentation, it has mentioned that- “Docker looks first for the image on your Docker host. If it can’t find it then it downloads the image from the public image registry”.

Please answer for my queries:

  1. Where does the docker checks for the image availability on the docker host? Will the docker creates any entry in any file once the image is downloaded from docker hub? If so, what is the location of the file?
  2. If image is not available locally why it downloads from default image registry? Can I change it to download from other repository if not found locally.

Thanks in advance,
Vishwa

Following article will help establishing your understanding.

Docker has concept of public & private repositories, as you pull images you provide the path from where the images are to be pulled from. Downloaded images are kept and organized in local path /var/lib/docker/