ldd --version
This should return a result similar to:
ldd (GNU libc) 2.17
Copyright (C) 2012 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
Written by Roland McGrath and Ulrich Drepper.
In this case, version 2.17 is installed.
yum list glibc
This should return a result similar to:
Loaded plugins: fastestmirror, langpacks, priorities
Loading mirror speeds from cached hostfile
3 packages excluded due to repository priority protections
Installed Packages
glibc.x86_64 2.17-55.el7_0.3 @system-updates-released
Available Packages
glibc.i686 2.17-55.el7_0.3 system-updates-released
In this case, 2.17-55.el7_0.3 is the package installed.