The websites of the White House, the British government and international media were hit by global outages on Tuesday.
Some social media platforms' websites were also affected, with some reports pointing to a glitch at US-based cloud computing services provider Fastly.
Messages such as “Error 503 Service Unavailable” and “connection failure” appeared on the websites of CNN, the Financial Times, The Guardian and France's Le Monde newspaper.
The White House website had an error message but was available again later.
The gov.uk websites remained unavailable at around 1030 GMT.
The BBC, New York Times and Bloomberg News were temporarily inaccessible, but also later returned.
Fastly said it was investigating “the potential impact to performance with our CDN services”, according to its website.
Most of Fastly's coverage areas were facing “Degraded Performance”, the website showed.
Separately, Amazon.com Inc's retail website also seemed to be down. Amazon was not immediately available to comment.
Nearly 21,000 Reddit users reported issues with the social media platform, while more than 2,000 users reported problems with Amazon, according to outage monitoring website Downdetector.com.
Amazon's Twitch was also experiencing an outage, according to Downdetector's website.