4 ms·
The point is that you don't know the IP address of the client, so you can't locate it. Most CDNs couple DNS (for a large region) and Anycast (within the region
by foobarbazetc 16y ago
The point is that you don't know the IP address of the client, so you can't locate it.
Most CDNs couple DNS (for a large region) and Anycast (within the region) -- they're not idiots.
- fleitz 16y agoHow does the CDN send data back to the client with out knowing its IP address? I'd like to know.
- foobarbazetc 16y agoThe point is that by the time you've heard from the client on the CDN (after resolving host to IP), they've already contacted a non-optimal CDN POP. Providing IP addresses (locations) to host queries is exactly what DNS is built to do. :)
- evgen 16y agoYou don't know the ip address of the real client when they are doing the dns lookup, so you start by assuming that they are close (in network terms) to the server that is performing the dns lookup. When you are not dealing with a borked dns service this assumption you will get into the right general region of the world. Once you are in the right region you can use anycast because within a relatively small region you are less likely to see big route shifts that will pop an anycast connection and hose your content delivery.