So the internet is a series of pipes, or tubes, whatever. This quintessential personal blog website is hosted somewhere in this inter connected mess of things. There’s a hierarchy of these pipes/tubes, and they all have some ever diminishing capacity as they head from a mythical center to the personal blog website.

When the bad guys want to DDoS the personal blog website they don’t go and figure out the correct amount they need to send to fill up that pipe/tube that directly connects the personal blog website, they just throw roughly one metric fton at it. This causes the pipes/tubes before the personal blog website to fill up too, and has the effect of disrupting all the other pipes/tubes downstream.

The result is your hosting provider is pissed because their infrastructure just got pummeled, or if you’re hosting that on your home/business ISP they also are pissed. In both cases they probably want to fire you now.

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q3k 5 hours ago | parent [-]

This is incorrect. Any decent host/ISP will instead (automatically, sometimes) emit a blackhole request for the given target IP address to their upstreams, causing the traffic to be filtered there (at the 'larger pipe'). In turn, these upstreams can also pass on the same blackhole request further up if necessary. This means the target is down from the point of view of the Internet, but there is no collateral damage.

See: BGP Blackhole Community (usually 65535:666).

	▲	ralferoo 3 hours ago \| parent [-]
		Interesting, I didn't realise blackholes were special-cased to allow BGP announcements of /32 instead of the usual /24 or larger. I'd just assumed (like the GP) that the traffic ended up on the target's closest network to the source and only then was it filtered.