Route 53 weight average and record sets returned

When processing a DNS query, Amazon Route 53 searches for a resource record set that matches the specified name and type. If a group of resource record sets have the same name and type, Amazon Route 53 selects one from that group. The probability of any one resource record set being selected depends on its weight as a proportion of the total weight for all resource record sets in the group:

For example, suppose you create three resource record sets for www.example.com. The three A records have weights of 1, 1, and 3 (sum = 5). On average, Amazon Route 53 selects each of the first two resource record sets one-fifth of the time, and returns the third resource record set three-fifths of the time.

AWS SLAs

The AWS services that have SLAs and the SLAs themselves can be found here:

http://aws.amazon.com/ec2/sla/

http://aws.amazon.com/route53/sla/

http://aws.amazon.com/rds/sla/

http://aws.amazon.com/s3/sla/

ELB : Some common questions

Q: Is a straight through reverse proxy possible with ELB? For example, a Wordpress instance that lives at my domain.com/blog.  Is it possible with ELB similar to apaches mod_proxy passthru functionality?

A: ELB does not support this feature.  Suggestions: Create a sub-domain like blogs.crafsy.com and have a separate DNS record + ELB for it.

Q: Is there a way to force traffic to a particular backend app server when fronted with ELB? 

A: ELB supports sticky sessions for ensuring that traffic within the same session flows to the same box.  For software release purposes, you could have a subdomain like test.craftsy.com and a separate DNS record + ELB.

Q: Can you have a zone apex in Route53 point at multiple ELB's? I assume this is so. (e.g. craftsy.com -> ELB1 (production a), ELB2 (production b)

A: Yes, if you use non-simple routing policy (weighted, latency or failover).