Customers type monstermarket.example, not www. That name, the zone's own, is the apex, and it already holds the NS and SOA records. A CNAME means "this name is really that one", so it cannot share a name with anything: no CNAME at the apex.

Alias records

An alias is Route 53's own kind of record, usually an A record (an AAAA alias does the same for IPv6). Instead of a value, it names a target, and Route 53 looks the target up and answers with its addresses.

The apex to the load balancer

An alias names the target's DNS name and the id of AWS's hosted zone for that target, not your zone's id: every load balancer reports it as CanonicalHostedZoneId.

aws elbv2 describe-load-balancers --names market-alb --query "LoadBalancers[0].[DNSName,CanonicalHostedZoneId]" --output text

{ "Changes": [ { "Action": "UPSERT", "ResourceRecordSet": {
  "Name": "monstermarket.example", "Type": "A",
  "AliasTarget": { "HostedZoneId": "Z35SXDOTRQ7X7K",
    "DNSName": "LB-DNS",
    "EvaluateTargetHealth": true } } } ] }

With the two values from the command above in place of Z35SXDOTRQ7X7K (it is the same for every load balancer in us-east-1) and LB-DNS, saved as apex.json:

aws route53 change-resource-record-sets --hosted-zone-id $ZONE --change-batch file://apex.json

There is no TTL: the answer carries the target's. With EvaluateTargetHealth, Route 53 treats the record as unhealthy while the load balancer has no healthy target (it matters with routing, next).

dig +short monstermarket.example

Two addresses, one per Availability Zone of the load balancer, and they change as it scales; the alias follows.

curl -s http://monstermarket.example/

Other targets

• CloudFront: zone Z2FDTNDATAQYW2, and the distribution must list the name (later this chapter).
• An S3 website: DNSName s3-website-us-east-1.amazonaws.com, zone Z3AQBSTGFYJSTF. S3 picks the bucket by the name the browser asked for, so the bucket must be named exactly like the record: promo.monstermarket.example. Otherwise S3 answers NoSuchBucket.
• Another record in the same zone: the zone's own id.

Give your own zone's id instead of the target's and Route 53 refuses: the alias target name does not lie within the target zone.