Update CentOS 7.x to specific version.

How to update CentOS 7.x to specific version or upgrading the Centos 7.x System Off-line with ISO and Yum.
In this tutorial we will show you, how to configure and use local yum repository and upgrade Centos 7.x to a specific version. For example 7.2 to 7.4

1) On Centos 7.2 server run the following Commands.
# yum install net-tools
# yum install wget
# yum install vsftpd
# systemctl start vsftpd.service
# systemctl enable vsftpd
# yum install createrepo

2) Disable SELinux
# vi /etc/selinux/config
Change: SELINUX=disabled
Save the file
# cat /etc/system-release
# reboot

3) Download Centos 7.4 and mount the .iso file.
# cd /root
# mkdir Software
# cd Software
# wget http://mirror.nsc.liu.se/centos-store/7.4.1708/isos/x86_64/CentOS-7-x86_64-Minimal-1708.iso
# cd /media
# mkdir ISO
# mount -o loop /root/Software/CentOS-7-x86_64-Minimal-1708.iso /media/ISO

4) Copy Centos 7.4 media content to the Server.
# mkdir /localrepo
# cp -rv /media/ISO/* /localrepo/

5) Configure a Local Repository.
First we need to backup current repository folder.
# cd /etc
# cp -r yum.repos.d yum.repos.d-old

Now delete all online repository and create local Repository File.
# rm -rf yum.repos.d/*
# vi yum.repos.d/local.repo

Add the following:
[centos74]
name=centos74
baseurl=file:///localrepo/
enabled=1
gpgcheck=0

Save the file and exit.

[centos74] – Name of the Section.
name = Name of the repository
baseurl = Location of the package
Enabled = Enable repository
gpgcheck= Enable secure installation

gpgcheck is optional (If you set gpgcheck=0, there is no need to mention gpgkey)
gpgkey = Location of the key

6) Now we need to update, and enable  the local repository.
# createrepo /localrepo/
# yum clean all
# yum repolist all

7) Update Centos 7.2 to 7.4 ussing local repos.
# yum update