I’ve stumbled upon this great list of materials you can use to get started on IT, and Networking in particular. I have to admit that some are new for me, even after being in this field for over 12 years.

2018-01-03 note, I’ve update the list with more resources

/r/ITCareerQuestions Wiki
/r/CSCareerQuestions Wiki
/r/Sysadmin Wiki
/r/Networking Wiki
/r/NetSec Wiki
/r/NetSecStudents Wiki
IT Certification Road Map
Cisco Training & certification Info Center
Juniper Networks Certification Programs
Microsoft Learning Info Center
Red Hat Certification Info Center
VMware Certification Info Center
Microsoft Learning Portal - Powered by EdX
Microsoft Virtual Academy
Microsoft MSDN Product Evaluation Center – Free Downloads
Microsoft TechNet Product Evaluation Center – More Free Downloads
Microsoft Azure Cloud Services Free Trial Center
Microsoft Training Info Center
Microsoft Ignite Training Convention Video Center
Microsoft MSDN Video Training Portal
Cisco / Networking
Stanford University Free Intro to Networking Online Course
Cisco Learning Center - How to Study for CCNA for Free
Professor Messer’s CompTIA Network+ Training Videos
Cybrary Free CCNA Training Videos
Cisco VIRL - Virtual Router & Firewall Training Tool
GNS3 Vault - Free Practice & Training Labs for Cisco Equipment
Cisco Live Training Convention Video Portal - Free Registration Required
Cisco Design Zone - Best Practices
PacketBomb - WireShark Training Center
NetCraftsmen - Network Consultants Blog
PacketPushers News & Podcasts
IOSHints - Ivan Pepelnjak’s Blog/site
Cumulus Networks SDN Technical Videos
SDX Central - SDN Resources
Information/Computer/Network Security
SANS Reading Room
SANS Certifications
BlackHat Conferences @ YouTube
DEFCON Conferences @ YouTube
RSA Conference @ YouTube
Carnegie Mellon SoftEng Institute @ YouTube
CMU’s Plaid Parliament of Pwning Competitive Hacking Team Blog
Cybrary - Open Source Security Learning
Krebs on Security blog
Google’s Security Blog
US CERT - Computer Emergency Response Team blog
ISC^2 - CISSP - Certified Information Systems Security Professional
Linux Resources
Linux Foundation - Intro to Linux for Free
Linux Foundation - Online Course Catalog - some free some paid
DigitalOcean Linux Tutorials
Docker Self-Paced Training
USENIX Site Reliability Enginering Convention 2014 Presentations - Free
USENIX Site Reliability Enginering Convention 2015 Presentations - Free
USENIX Large Installation System Administration Conference 2014 Presentations - Free
USENIX Large Installation System Administration Conference 2015 Presentations - Free
PuppetConf Convention Videos 2014 - Free Registration Required
PuppetConf Convention Videos 2015 - Free Registration Required
ChefConf Convention Videos 2015
Ansible Video Resources - Including AnsibleFest Convention Videos
SaltStack Video Resources
VMware Resources
VMWorld Convention Session Playback
VMWare Hands-On-Labs Training Labs
The Best of Cisco Live
^(Cisco Live is Cisco’s annual Technology expo & training convention.)
^(All of these presentations are available for free here: http://www.ciscolive.com/online - Many with video presentations of the lectures.)
BRKARC-3001 - Cisco Integrated Services Router G2 - Architectural Overview and Use Cases (2013)
BRKARC-3001 - Cisco Integrated Services Router - Architectural Overview and Use Cases (2016)
BRKARC-2001 - Cisco ASR1000 Series Routers: System & Solution Architectures (2016)
BRKCRS-3147 - Advanced Troubleshooting of the ASR1K and ISR (IOS-XE) made easy (2016)
BRKARC-1009 - Cisco Catalyst 2960-X Series Switching Architecture (2016)
BRKARC-3438 - Cisco Catalyst 3850 and 3650 Series Switching Architecture (2016
BRKCRS-3146 - Troubleshooting Cisco Catalyst 3650 / 3850 Series Switches (2016)
BRKARC-3445 - Cisco Catalyst 4500E Switch Architecture (2016)
BRKCRS-3142 - Troubleshooting Cisco Catalyst 4500 Series Switches (2015)
BRKARC-3465 - Cisco Catalyst 6800 Switch Architectures (2016)
BRKCRS-3143 - Troubleshooting Cisco Catalyst 6500 / 6800 Series Switches (2015)
BRKARC-2222 - Cisco Nexus 9000 Architecture (2015)
BRKDCT-3101 - Nexus 9000 (Standalone) Architecture Brief and Troubleshooting (2016)
BRKCRS-1500 - Wired LAN Deployment Using the Cisco Validated Design for Campus (2016)
BRKCRS-2031 - Enterprise Campus Design: Multilayer Architectures and Design Principles (2016)
BRKCRS-2501 - Campus QoS Design-Simplified (2016)
Cisco Design Zone: Cisco Validated Designs for Campus Networks
Cisco Design Zone: Cisco Validated Designs for Branch Office Networks
BRKDCT-2218 - Data Center Design for the Midsize Enterprise (2016)
BRKSAN-2449 - Storage Area Network Extension Design and Operation (2015)
BRKSAN-2883 - Advanced Storage Area Network Design (2016)

Enjoy it! :)

Credits: VA_Network_Need via reddit.