Linux Link Following are important link releated to linux: Ubuntu Debian releated: 1: https://www.debian.org/doc/manuals/debian-reference/ch02.en.html 2: https://wiki.debian.org/DebianPackageManagement AD Integration Link: http://www.overclockers.com/forums/showthread.php/709625-HowTO-Sync-Active-Directory-with-Directory-Server Squid Link: 1: https://www.linuxnix.com/troubleshooting-squid-reverse-proxy-server/ Shell Scripting: 1: https://bash.cyberciti.biz/guide/Main_Page 2: http://matt.might.net/articles/bash-by-example/ 3: http://www.freeos.com/guides/lsst/ Mail Relay: https://easyengine.io/tutorials/linux/ubuntu-postfix-gmail-smtp/ https://devanswers.co/configure-postfix-to-use-gmail-smtp-on-ubuntu-16-04-digitalocean-droplet/ Perl: www.perltutorial.org DNS: 1: https://www.interserver.net/tips/kb/dns-dns-hierarchy/ 2: https://en.wikipedia.org/wiki/Domain_name_registry 3: https://en.wikipedia.org/wiki/DNS_zone 4: ht