As I understand it, BGP provides redundancy between ISP links. So if I am hosting a website (ex: 12.1.22.1; www.mywebsite.com) and the link to the ISP that holds that public subnet (12.1.22.1) goes down, then BGP will redirect traffic to the secondary ISP and the website would still be viewable to the public.
Here is my question... couldn't I just add two dns records such as 12.1.22.1 www.mywebsite.com and 65.1.12.3 (different ISP subnet) www.mywebsite.com, so that if the first ISP goes down, the public will still be able to find it by resolving the second dns record.
Using multiple dns records instead of BGP??www.microsoft.com
To go along with the first response, all that will get you is that roughly half of the people will be able to access the functional site. What you're referring to is called "round-robin DNS". It's more of a load balancing rather than a fault-tolerant solution. It works fine for MX records, because mail servers fall back onto secondary MX records if the primary does not respond. Unfortunately, when a web client queries the A record, it doesn't care if it's actually functional or not.
Using multiple dns records instead of BGP??microsoft windows xp internet explorer
A client machine will simply respond to the first dns address it is given. If that site is unavailable it reports this and stops looking. Any further request will probably have the same result.
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