When I lived in Malmö my ISP DNS would result in Akamai CDN content being served from Stockholm rather than Copenhagen which was a lot closer and faster.
When I switched to 1.1.1.1 this problem went away
Or they have a vested interest in keeping customers hitting specific locations which may be suboptimal for the end user.
Around here some rather have you stay in their preferred AS as much a possible and stick to DCs in Paris than Frankfurt (to direct peering?), even though FRA is a stone throw away. This conveniently disappears when using ISP-independent DNS (at the cost of sometimes, some regional-specific content not being primed in the CDN, which I think is why sometimes downloads start slow then shoot way up).
e.g tested quickly today with mtr:
- Home to Akamai PAR1 = 8 hops:
1-5: ISP, 5 hops
6-7: Zayo, 2 hops
8: Akamai intx-par1
best: 22, worst: 80, stdev: 10
1-2: ISP, 2 hops
3: Akamai intx-fra1
best: 27, worst: 51, stdev: 4
Does DNS care about geolocation?
It measures distance in b/s dose it not?
It's a mess.
If google would work, I could find the old forum threads about the problem. But not any more.
Oh I probably should have mentioned. The problem seems to have been global. Not any particular ISP.