TopolearnDNS is how users find your service, and Route 53's routing policies are a key tool for releases and disaster recovery.
Route 53 is AWS's DNS service. A hosted zone holds records for a domain; public zones answer the internet, private zones answer only inside associated VPCs. To use a zone for a domain registered elsewhere, set the registrar's NS records to the four name servers Route 53 assigns.
Record types are the usual ones (A, AAAA, CNAME, MX, TXT, CAA) plus a Route 53 extension, the alias record. An alias points a name at an AWS resource such as an ALB, CloudFront distribution, S3 website or another record. Unlike a CNAME it works at the zone apex (example.com), follows the target's changing IPs automatically, and queries to AWS targets are free.
TTL controls how long resolvers cache answers. Lower it a day before a planned migration; keep it moderate otherwise.
Routing policies let one name return different answers:
- Weighted: split traffic, for example 90/10 for a canary.
- Latency: answer with the Region closest in latency to the user.
- Failover: primary and secondary, switching when a health check fails.
- Geolocation / geoproximity: by user location, for compliance or localisation.
- Multivalue: up to eight healthy records, simple client-side balancing.
Health checks probe endpoints (or watch CloudWatch alarms) and remove unhealthy answers. Remember DNS failover is only as fast as TTLs and client caching allow; it is a Region-level tool, not a substitute for load balancers within a Region.
Example
cat > change.json <<'EOF'
{"Comment": "Point the API at the ALB",
"Changes": [{"Action": "UPSERT",
"ResourceRecordSet": {
"Name": "api.example.com", "Type": "A",
"AliasTarget": {
"HostedZoneId": "Z32O12XQLNTSW2",
"DNSName": "dualstack.web-alb-1234567890.eu-west-1.elb.amazonaws.com",
"EvaluateTargetHealth": true}}}]}
EOF
aws route53 change-resource-record-sets --hosted-zone-id Z0123456789ABCDEFGHIJ \
--change-batch file://change.json --query ChangeInfo.Status --output text
# PENDING (INSYNC within about a minute)
dig +short api.example.com
# 52.48.12.34
# 34.250.7.89Remember
- Hosted zones hold records; delegate with NS records at the registrar
- Alias records work at the apex and track AWS resources' IPs
- Weighted, latency and failover policies steer traffic
- DNS changes are bounded by TTL and client caching
Watch out for
- Using a CNAME at the zone apex, which DNS forbids; use an alias record.