Revealed: Why Facebook, WhatsApp, Instagram suffered the worst outage

Social media platforms Facebook, WhatsApp, Instagram and Messenger suffered a major outage and went down for millions of users, including in India, on Monday evening, as they were unable to send or receive messages on social media platforms.

People took to Twitter to report the problems they were facing with Facebook family apps, including posting memes and GIFs.

The outage, which lasted six hours on Monday, not only made it impossible for the company's 3 billion-plus users to access Facebook and its Instagram and WhatsApp services, it also affected internal systems for employees, CNBC reported.

The company said that the operations were disrupted by configuration changes on backbone routers.

"Our engineering teams have learned that configuration changes on the backbone routers that coordinate network traffic between our data centers caused issues that interrupted this communication. This disruption to network traffic had a cascading effect on the way our data centers communicate, bringing our services to a halt," the engineers said in a statement on Facebook`s website.

"Our services are now back online and we`re actively working to fully return them to regular operations. We want to make clear at this time we believe the root cause of this outage was a faulty configuration change," the statement said.

The outage was so bad that engineers who were tasked with helping resolve service issues were unable to even log on and get involved to fix the problems, one person familiar with the situation told the news platform.

As per web Security company Cloudflare, the DNS names for Facebook and its affiliated services WhatsApp and Instagram stopped resolving and their infrastructure IPs were unreachable. "At 15:58 UTC we noticed that Facebook had stopped announcing the routes to their DNS prefixes. That meant that, at least, Facebook’s DNS servers were unavailable," it said.

After remaining down for around six hours, Facebook's apps and services including Whatsapp returned to normal operations online on Tuesday.

Whatsapp thanked its users around the world for being patient while the WhatsApp team was trying to restore the application.

Taking to Twitter, Whatsapp said, "We're now back and running at 100%. Thank you to everyone around the world today for your patience while our teams worked diligently to restore WhatsApp. We truly appreciate you and continue to be humbled by how much people and organizations rely on our app every day.