03 · Split-horizon: one FQDN, three answers
The same name exists in all three private zones with different records. Whichever VPC's Route 53 Resolver answers decides the result — so each site resolves to its own site-local target.
Records
| FQDN | Zone A Office · ap-ne-1 | Zone B Taichung · ap-ne-1 | Zone C Taipei · ap-ne-1 |
|---|---|---|---|
api.corp.internal | 10.1.20.5 | 10.2.20.5 | 10.3.20.5 |
db.corp.internal | 10.1.30.8 | 10.2.30.8 | 10.3.30.8 |
vault.corp.internal | 10.1.40.2 | 10.2.40.2 | 10.3.40.2 |
Prefix rule
3 cases per zone shown. Records share the zone's /16 prefix, so resolution naturally stays inside the originating site's VPC + IDC pair.