The easiest way to install Ansible is by adding EPEL (Extra Packages for Enterprise Linux) repository.

Use below command to add epel repository.

[root@ansible-server ~]# rpm -ivh http://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
Retrieving http://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
warning: /var/tmp/rpm-tmp.C01zA7: Header V3 RSA/SHA256 Signature, key ID 352c64e5: NOKEY
Preparing... ################################# [100%]
Updating / installing...
 1:epel-release-7-11 ################################# [100%]
[root@ansible-server ~]# 

Verify the epel repository

[root@ansible-server ~]# yum repolist |grep epel
epel/x86_64 Extra Packages for Enter 12,353
[root@ansible-server ~]#

After added epel repository, we can install Ansible using following command

[root@ansible-server ~]# yum install ansible -y

After installed successfully, we can verify the version by executing below command

[root@ansible-server ~]# ansible --version
ansible 2.4.2.0
 config file = /etc/ansible/ansible.cfg
 configured module search path = [u'/root/.ansible/plugins/modules', u'/usr/share/ansible/plugins/modules']
 ansible python module location = /usr/lib/python2.7/site-packages/ansible
 executable location = /bin/ansible
 python version = 2.7.5 (default, May 3 2017, 07:55:04) [GCC 4.8.5 20150623 (Red Hat 4.8.5-14)]
[root@ansible-server ~]#