$apt policy base-files
base-files:
  Installed: 10.1ubuntu2.4
  Candidate: 10.1ubuntu2.4
  Version table:
 *** 10.1ubuntu2.4 500
        500 [local mirror]/us.archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     10.1ubuntu2.2 500
        500 [local mirror]/us.archive.ubuntu.com/ubuntu bionic-security/main amd64 Packages
     10.1ubuntu2 500
        500 [local mirror]/us.archive.ubuntu.com/ubuntu bionic/main amd64 Packages