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: docs in Miami (MIA) · D-48

Runbook D-48 for DNS in Miami (MIA). Marker xserv-d-67ce63b544a2. This page covers docs for LATAM operators, not a worldwide average.

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: Why it matters on this continent

Design for DNS on letter D starts in São Paulo (GRU). Runbook d-01 keeps a single owner, a written rollback, and a traffic split that can be reversed without a global freeze. Neighbors in Santiago only take overflow after the local pool fails a health window.

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 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.