RPM repo not found connection errors on Centos Redhat duplicate problems

yum -y update command failing

Command line will show messages like

xxx is outdated and v abc will be installed
but at the end it shows duplicate binary, please remove duplicate first.

Process

Backup first
Integrity Check
Find Problems
Identify duplicates
Clean duplicates
re build conf cache
update command
remove backup file .prev if successfully solved

\cp -r /var/lib/rpm /var/lib/rpm.prev
yum-complete-transaction
package-cleanup --problems
package-cleanup --dupes
package-cleanup --cleandupes
yum clean all
rpm --rebuilddb
yum update
# if all went OK run 'rm -rf /var/lib/rpm.prev'

Other possible solution

1. Update DNS to google dns 8.8.8.8 and 8.8.4.4 or freenom dns 80.80.80.80 and 80.80.81.81

system-config-network

2. Restart internet while maintaining SSH session (you wont be logged out)

/etc/init.d/network restart

Compressing images directly on web server – Better Pagespeed tips

for png, install on centos using command

yum install optipng

for a single image

optipng -o5 filename.png

move to folder in which pngs are stored and use the following command:

for i in *.png; do optipng -o7 -strip all  -quiet "$i"; done

this will overwrite all pngs, o7 is switch for number of tries. o5 will be less time consuming though. -quiet makes it muted, outputs nothing.
-strip all will try to remove all meta data.
you can use -preserve to preserve the modification date.
also try -keep, if you want to save backup of each file