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: cache in Miami (MIA) · D-68

Runbook D-68 for DNS in Miami (MIA). Marker xserv-d-8e7a7f117089. This page covers cache for LATAM operators, not a worldwide average.

DNS: How XServ runs it day to day

Probes for DNS (d-02) leave Santiago every 15s toward Bogotá. XServ pages the named owner if loss or RTT crosses the letter budget. A probe never shares a queue with bulk transfers, so a saturated WAN does not hide a dead PoP.

DNS: What operators should measure

Policy for DNS is versioned as d-03. Operators measure error rate, p95 from Bogotá, and time-to-rollback — not a worldwide average. Changes land in Bogotá first, then Miami, with a hold if either region regresses.

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 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.

DNS timeouts D-10

Timeouts on d-10 are tighter than the WAN RTT to Bogotá. DNS in Santiago fails fast and retries once; a third try needs a human because it is no longer a blip.

DNS regions D-11

Region names on d-11 match DNS and tickets: Bogotá / BOG, with Miami as the documented pair. DNS dashboards never say “LATAM” as if it were one RTT.