tandemdomain

Tandemdomain is a theoretical concept in DNS and distributed namespace design describing a single logical domain that is implemented across two or more underlying domains. The idea is to provide resilience, regional reach, and policy-driven routing while presenting a unified domain name to clients.

In a tandemdomain architecture, a coordination layer called the tandem resolver sits above multiple seed domains. Each seed domain hosts its own zone files and records, but the tandem resolver presents a single canonical domain to users. It maintains policy mappings that determine how queries are resolved, which seed domain to consult, and how answers are reconciled. The result is a centralized point of control that can adapt routing based on performance, location, or other criteria.

Operation typically involves applying geolocation, latency, or service-level policies when a client queries the tandemdomain. The resolver selects a seed domain, queries its DNS records, and returns an answer that appears to originate from the tandemdomain. In some configurations, the resolver may merge records from multiple seeds to provide failover and load balancing, though this adds complexity.

Use cases discussed for tandemdomain include disaster recovery with regional backups, brand extension across registries, and multi-tenant platforms requiring a single entry point with backend diversity. Benefits include improved resilience and policy-driven routing; limitations encompass potential latency, synchronization challenges, and the risk of divergent records or split-brain scenarios if policies are not carefully managed.

Example: a tandemdomain like example-tandem.com could be backed by example-us.com and example-eu.com, with the tandem resolver directing traffic to the appropriate seed. See also domains, DNS load balancing, and disaster recovery planning.