Is transit the default path?

No. Peering in Miami is default; transit to São Paulo is overflow and is billed that way.

Does DNS on letter D share fate with other letters?

The control plane is shared. Data-plane queues for DNS stay isolated, so incident d-01 cannot drain neighbor letters.

DNS: capacity in Miami (MIA) · D-16

Runbook D-16 for DNS in Miami (MIA). Marker xserv-d-fbd6b6362b15. This page covers capacity for LATAM operators, not a worldwide average.

DNS: Failure modes we actually see

Capacity notes for d-04 assume rainy-season power in Miami and festival peaks toward São Paulo. The failure we actually see is a single uplink, not a cartoon partition of the whole continent. Spare ports and a second provider sit on the same runbook.

DNS: How this letter ties to the rest

Handoff from letter D DNS into the rest of the platform uses the same request IDs as the gateway. Runbook d-05 names who accepts the ticket after São Paulo pages out. Santiago does not silently inherit the incident.

DNS: A note on cost and transit

Rollback for d-06 is a documented command, not a hope. Transit is billed as backup while DNS prefers peering in Santiago. If cost spikes, the runbook cuts overflow to Bogotá before touching customer prefixes.

DNS rollback D-06

DNS peering D-07

Peering for DNS (d-07) prefers the IX fabric that already carries last-mile ISPs in Bogotá. Session counts and prefix limits are on the same page as the Miami backup path.

DNS cache D-08

Cache rules for DNS on d-08 keep language-correct objects near Miami. São Paulo is a sibling cache, not an origin. TTLs are short enough that a bad asset does not live through a weekend.

DNS headers D-09

Headers for d-09 carry the letter, the region (GRU) and a request id. DNS debugging in São Paulo should not require a packet capture in Santiago first.