docker pull error when do not add domain prefix

[cnlxh]

This is no error when:

docker pull xxx.xxx.com/library/nginx

but it does not work when:

docker pull nginx

I have been write docker config

root@k8s-worker1:~# cat /etc/docker/daemon.json
{
  "registry-mirrors": ["https://xxx.xxx.com"],
  "exec-opts": ["native.cgroupdriver=systemd"]
}

and, I verify it at docker info:

root@k8s-worker1:~# docker info | tail
 Docker Root Dir: /var/lib/docker
 Debug Mode: false
 Experimental: false
 Insecure Registries:
  ::1/128
  127.0.0.0/8
 Registry Mirrors:
  https://xxx.xxx.com/
 Live Restore Enabled: false

so how can i pull image without add the domain prefix when i pull it.