Ask HN: How does Twitter stream new tweets even when internet connection is down

My internet was down for an hour, none of the host were able to be resolved except twitter.com probably because of the cache I'm guessing.

In my Tp-Link router (Archer) it showed `Poor network` on the PPPoE connection with the ISP. (DNS servers down?)

Although the media content like images and videos weren't able to resolve twitter was able to stream new tweets with the text content.

I am not a network expert. What am I missing here?