They're all down, right? That's because much of the internet is broken due to one massive cyber attack that is affecting systems run by Dyn, one of the largest providers of internet services in the world. The distributed denial of service (DDoS) attack notice was posted on Dyn's website:
“Starting at 11:10 UTC on October 21th - Friday 2016 we began monitoring and mitigating a DDoS attack against our Dyn Managed DNS infrastructure. Some customers may experience increased DNS query latency and delayed zone propagation during this time.”
Dyn, which provides managed domain name service via its Anycast Network, said on Friday that the DDoS attack has led to popular sites either not loading or being slowed down. The incident appears to be affecting large parts of the internet for Dyn's customers in the both the US and UK. With DDoS attacks, servers are hit with so many requests that they stop responding.
If you find that you're still able to get online, or that some devices are able to, your DNS information is probably cached by some networks, which can grant you access even if servers are down. Dyn's engineers are working to mitigate the issue. It will post an update when it knows more.