Also make sure that your DSL and Cable provider are not the same ISP. While it would be convenient to use one ISP for both DSL and cable, it's not full independent because a core network issue could affect both. I would also suggest not using ISPs that have their network cores in the same building.
For example, if you were in Montreal, I might suggest DSL from TekSavvy (network core at 151 Front in Toronto) and cable from Electronic Box (network core at cologix in Montreal). At that point they would be completely independent.
In Ontario, though, I'm not sure who has a completely different network core.
The reason that I suggest this is because there have been past instances where an incident at 151 Front has caused outages to ALL companies hosted in the building, so even though (for example) Caneris and TekSavvy have completely independent networks, they both host in the same building, and so that time Peer1 had their UPS explode and the fire department blockaded the building, everybody had problems.--
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