This directory (and version of CentOS) is deprecated. For normal users,
you should use /7/ and not /7.3.1611/ in your path. Please see this FAQ
concerning the CentOS release scheme:

If you know what you are doing, and absolutely want to remain at the 7.3.1611
level, go to for packages.

Please keep in mind that 7.3.1611 no longer gets any updates, nor
any security fix's.