Route 53 routing policies: failover, weighted, latency, geo

Try 3 questions on this

Pick an answer to see why each option is right or wrong.

1. Six EC2 instances in one Region serve an internal API directly, with no load balancer, and the team is not permitted to add one. Clients resolve one name and connect to whichever address they receive. When an instance fails, clients must stop being sent to it, and traffic should be spread across the healthy instances. Which approach will meet these requirements?

   Right. In the game that’s Renown for your Design Resilient Architectures building.

   Not that one: D is right. In the game your Design Resilient Architectures building would lose a little Renown, and this question would come back later.

   Your answerA.Create one simple routing record listing all six addresses, because Route 53 returns them in random order and spreads the load.Simple routing is "for a single resource that performs a given function for your domain" and associates no health check with its values.Your answerB.Create a failover record pair so that clients move to a healthy instance whenever the primary stops responding.Active-passive: one instance serves at a time, so five of the six sit idle.Your answerC.Create weighted records with equal weights for the six instances, so that each receives a sixth of the queries.Distributes queries in the proportions you set and does not, by itself, answer the requirement that failed instances stop being returned as a group of healthy answers.The answerD.Create a multivalue answer record for each instance with a health check, so that Route 53 returns up to eight healthy records at random.Multivalue answer routing is the policy defined by returning healthy records, several at a time. "Multivalue answer routing policy - Use when you want Route 53 to respond to DNS queries with up to eight healthy records selected at random." Both halves of the requirement are in that sentence: the health check attached to each record keeps failed instances out of the answer, and the random selection spreads clients across the rest. Weighted routing is the tempting alternative because equal weights do spread traffic, but its purpose is "to route traffic to multiple resources in proportions that you specify", which is a different requirement from returning only the healthy ones as a set.

   Written from docs.aws.amazon.com/Route53/latest/DeveloperGuide/routing-policy.html

2. A company serves example.com from an Application Load Balancer in one AWS Region, and the domain is hosted in Amazon Route 53. When the application is down, visitors must automatically receive a static maintenance page served from Amazon S3. The company does not want to run any servers for the maintenance page. Which combination of steps should a solutions architect take to meet these requirements? (Select TWO.)

   Right. In the game that’s Renown for your Design Resilient Architectures building.

   Not that one: A,C is right. In the game your Design Resilient Architectures building would lose a little Renown, and this question would come back later.

   Your answerA.Create a failover alias record for example.com as the primary record, route it to the load balancer, and set Evaluate target health to Yes.Your answerB.Create a simple alias record for example.com that routes to the load balancer with Evaluate target health set to Yes, and a second simple record for the bucket.Relies on a setting that does nothing here. Evaluate target health has no effect for simple routing, and Route 53 answers with a lone simple record whether or not its target is healthy.Your answerC.Create an S3 bucket named example.com, configure it for static website hosting, and route a secondary failover alias record for example.com to its website endpoint.Your answerD.Create an S3 bucket named example-maintenance-page, configure it for static website hosting, and route a secondary failover alias record for example.com to its website endpoint.Gets the bucket's name wrong. An alias record for an S3 bucket must have the bucket's name, so a record for example.com cannot route to a bucket with another name.Your answerE.Create the secondary failover record for example.com as a CNAME record pointing to the bucket's website endpoint.Puts a CNAME at the zone apex. Route 53 does not support a CNAME record with the same name as the hosted zone, and example.com is that name.

   Show the full explanation and doc quotes

   A lets the targets behind the load balancer decide; for Application Load Balancers with Evaluate Target Health set to Yes, "Route 53 routes queries to the load balancer based on the health of the target groups that are associated with the load balancer" (Route 53 guide, 'Values specific for failover alias records'). C supplies a secondary that works, because of a naming rule for S3 buckets: "The name of the record must match the name of your Amazon S3 bucket." The same entry adds: "In addition, you must configure the bucket for website hosting." D builds the same thing around a bucket whose name differs from the record, so A,D looks complete and cannot work.

   Written from docs.aws.amazon.com/Route53/latest/DeveloperGuide/resource-record-sets-values-alias-common.html

3. A company uses Amazon Route 53 geoproximity routing with rules for resources in the US East (N. Virginia) and US West (Oregon) Regions and for a data center in Johannesburg that is identified by latitude and longitude. The company must send more South American users to US East (N. Virginia), and must move users gradually away from the Johannesburg data center before it closes. Which actions should be taken to meet these requirements? (Select TWO.)

   Right. In the game that’s Renown for your Design Resilient Architectures building.

   Not that one: A,E is right. In the game your Design Resilient Architectures building would lose a little Renown, and this question would come back later.

   Your answerA.Set a positive bias on the geoproximity rule for the US East (N. Virginia) Region.Your answerB.Set a bias of +150 on the geoproximity rule for the US East (N. Virginia) Region.Uses a value outside the range. A positive bias is an integer from 1 to 99, so +150 cannot be set.Your answerC.Set a positive bias on the geoproximity rule for the Johannesburg data center so that Route 53 shrinks the area it serves.Reverses the sign. A positive bias expands the area a resource serves, so Johannesburg would draw more users, not fewer.Your answerD.Set a negative bias on the geoproximity rule for the US East (N. Virginia) Region so that Route 53 expands the area it serves.Reverses the sign. A negative bias shrinks the area US East (N. Virginia) serves and hands users to adjacent regions.Your answerE.Set a negative bias on the Johannesburg data center's geoproximity rule.

   Show the full explanation and doc quotes

   And "To shrink the size of the geographic region from which Route 53 routes traffic to a resource, specify a negative bias of -1 to -99. Route 53 expands the size of adjacent regions." Lowering the Johannesburg bias in steps moves its users to its neighbours gradually.

   Written from docs.aws.amazon.com/Route53/latest/DeveloperGuide/routing-policy-geoproximity.html