apt-cache policy libc6 dpkg apt install-into
libc6:
  Installed: 2.17-3
  Candidate: 2.17-3
  Version table:
 *** 2.17-3 0
        650 http://ftp.us.debian.org/debian/ testing/main amd64 Packages
        100 /var/lib/dpkg/status
dpkg:
  Installed: 1.15.8.13
  Candidate: 1.16.10
  Version table:
     1.16.10 0
        650 http://ftp.us.debian.org/debian/ testing/main amd64 Packages
 *** 1.15.8.13 0
        100 /var/lib/dpkg/status
apt:
  Installed: 0.9.7.8
  Candidate: 0.9.7.8
  Version table:
 *** 0.9.7.8 0
        650 http://ftp.us.debian.org/debian/ testing/main amd64 Packages
        100 /var/lib/dpkg/status
N: Unable to locate package install-into