Looks like this problem: linux - Issues with Network interface card in CentOS 7 - Super User
You need drivers for the Intel 100Mb interface:
When I installed the operating system I found I were missing two NICs from network manager and when we used the command:
~] # lspci -k -nn | grep -i ‘ethernet’
I found out that we have the card installed but they were not
performing the task. Both of them were of same king and it was obvious
that these routers were missing drivers, I tried to search for drivers
and found the drivers on elrepo and the driver name was kmod-e100. I
tried installing it using:
~] # yum install kmod-e100
but it didn’t work and after more research I found out that to
install this driver you have to declare the repositories by using this
command:
~] # rpm -Uvh http://www.elrepo.org/elrepo-release-7.0-2.el7.elrepo.noarch.rpm
and now when I used the same yum command it worked.