monitoringobservabilityoutage

Monitoring Signals That Precede Big Cloud Outages: Build Your Early-Warning Dashboard

ppyramides

2026-02-01

11 min read

Build an early‑warning dashboard that correlates DNS errors, CDN 5xx spikes and BGP anomalies to detect outages faster.

Your team got paged at 03:14 — but could you have seen it coming?

Big cloud outages rarely arrive out of nowhere. They surface as small, correlated anomalies across DNS, CDN telemetry and BGP feeds — signals that most teams ignore until the incident is already full‑blown. If you operate production services in 2026, you need an early‑warning dashboard that brings those signals together, enriches them with internet‑scale context, and triggers meaningful alerts before customer impact becomes widespread.

The landscape in 2026: why early signals matter more than ever

Late 2025 and early 2026 brought a string of high‑visibility outages (multiple public cloud and CDN incidents) that reinforced a core reality: monoculture in telemetry and single‑provider monitoring create blind spots. At the same time, adoption of technologies like RPKI and DNS over HTTPS (DoH) has grown, but coverage is still incomplete — creating mixed signals you must reconcile.

Operational teams now run more distributed edge workloads, rely on multi‑CDN strategies, and depend on third‑party DNS and managed network services. That increases attack surface and complexity. A hybrid approach — pairing internal app metrics with internet telemetry sources — is the only way to reliably detect the precursors of large outages.

Which signals reliably precede major outages (and why)

Below are the telemetry classes that consistently show early degradation before a large outage. Treat each as part of a correlated pattern rather than a lone alarm.

1) DNS errors and anomalies

Why it matters: DNS is the first dependency every client touches. DNS failures (timeouts, SERVFAILs, truncated responses) frequently appear before users see app errors — especially when authoritative or resolver networks are degraded.

Timeout rate: A rising fraction of DNS queries that time out or exceed your client’s resolver timeout is an early signal of network or resolver instability.
SERVFAIL and FORMERR spikes: These indicate authoritative server stress, misconfigurations, or rate limits being hit.
EDNS / truncation / TCP fallback increases: A growing number of truncations (TC bit set) and more clients using TCP fallback shows path MTU or UDP packet loss problems.
NXDOMAIN anomalies: Rising NXDOMAINs for known good hosts often point to cache poisoning effects, mis‑applied DNS policies, or zone corruption during a deployment.

2) CDN telemetry: 5xx spikes and origin latency

Why it matters: CDN 5xx errors are frequently the first visible symptom when origin pools get overwhelmed, an entire POP loses connectivity to origin, or an upstream provider is failing.

5xx rate by POP and edge: Sudden 5xx spikes in a subset of POPs indicate localized network or cache failures; global 5xx spikes suggest origin or control plane outages.
Cache miss rate increase: Increasing cache misses (also observed as rising origin requests) can overload upstream systems and precede 5xx spikes.
TLS handshake failures: Rising TLS errors at the CDN edge often indicate certificate issues, client cipher mismatches, or upstream TLS termination problems.
Origin latency and connect time: A growing tail in origin connect/TTFB precedes 5xx trends and is a practical early indicator.

3) BGP anomalies and route instability

Why it matters: BGP anomalies change the paths your customers’ traffic takes. Withdrawals, hijacks, and flaps cause sudden regional degradations and often underlie “it’s intermittent across the US” outages reported by status pages.

Prefix withdrawals and reachability changes: A sharp uptick in withdrawals for prefixes you originate or depend on is a show‑stopper signal.
Origin AS changes (MOAS): Multiple origin AS announcements for the same prefix (MOAS) or sudden origin AS changes can be malicious (hijack) or accidental (misconfiguration).
AS path anomalies and prepending: Unexpected AS path modifications and sudden prepends indicate routing policy changes impacting latency and traffic steering.
RPKI ROA invalids: In 2026 more operators use RPKI; a sudden rise in ROA invalids for your prefixes should trigger investigation.

4) Client geography and synthetic check divergence

Why it matters: Viewer‑side metrics (real user monitoring) plus active synthetic checks from diverse geographies reveal where the impact starts and how it spreads. A synthetic is often faster to spot a partial outage because it’s consistent and controllable.

How to collect these signals: data sources and tools

Mix internal telemetry with third‑party internet measurement services to avoid provider blind spots. Here are practical, proven sources for each signal class.

DNS: Bind/Unbound metrics, CoreDNS metrics (Prometheus), RIPE Atlas DNS measurements, DNS provider logs (Cloudflare, AWS Route 53), and resolver telemetry (e.g., public DoH/DoT providers).
CDN: CDN provider metrics (edge 5xx by POP, cache hit/miss, TLS errors), WAF logs, edge access logs, and synthetic edge checks via multi‑CDN probes.
BGP: RouteViews, RIPE RIS, BGPStream/CAIDA, public looking glasses, and if available, your IX/peer router OpenBMP or BGPMon feeds. RPKI validators (e.g., Routinator) for ROA validation.
Synthetic and RUM: Global synthetic checks (from providers like Uptrends, Catchpoint, or homegrown RIPE Atlas probes) plus RUM from users (RUM latency, errors by region).
Logs and traces: Edge and origin logs shipped to Grafana Loki/ELK and distributed traces from OpenTelemetry to correlate latency increases to code paths.

Designing an early‑warning dashboard: what to show and how to prioritize

Your dashboard must be action‑first: give operators a single pane of truth where correlated signals are obvious. Design it in tiers: global summary, regional hot spots, and deep‑dive panels.

Top row — the one‑glance health bar

Global health score (weighted composite of DNS, CDN 5xx rate, BGP stability, synthetic pass rate).
Active degradation count (number of regions/POP/prefixes with signals).
Open incident indicator + most recent annotation (deployment, config change, maintenance window).

Second row — correlated time series

DNS timeouts and SERVFAILs (time series, by resolver/region).
CDN 5xx rate by POP and global rollback (5m / 1h windows).
BGP withdrawals and origin AS changes (events per minute, mapped to prefixes/ASNs).

Third row — regional map & tables

World/continent map with POPs and BGP reachability overlays.
Top 10 prefixes by withdrawal rate and ROA status.
Top 10 POPs by 5xx increase, with cache miss ratio and origin latency.

Deep dives — logs, traces, and enrichment

Correlated raw logs for a selected POP/prefix/time window (Loki/ELK).
Trace waterfall for slow transactions reaching origin (OpenTelemetry).
An enrichment panel linking to recent change events: deploys, BGP config changes, DNS delegations, and provider status feeds.

Actionable detection heuristics and example thresholds

Detection requires combining absolute thresholds with relative baselining. Below are practical heuristics used by SRE teams in 2026.

DNS timeout rate: Alert if DNS timeouts exceed 2x baseline and absolute > 0.5% of queries over a 5m window.
SERVFAIL spike: Alert if SERVFAIL rate rises >3x baseline and accounts for >0.2% queries over 5m.
CDN 5xx by POP: Medium alert if a POP 5xx rate >1% and >5x baseline; high alert if >5% or if >3 POPs report simultaneous spikes.
Cache miss surge: Alert when cache miss rate increases by >30% and origin RPS increases correspondingly.
BGP withdrawals: Alert when there are >20 withdrawals per minute for your announced prefixes, or when ROA invalids increase by >10% relative to baseline.
Synthetic/RUM divergence: Alert when synthetic checks fail from >=3 distinct regions while global RUM error rate increases by >50% in those regions.

Example observability pipeline: Prometheus + Grafana + BGPStream

Below is a concise, practical integration pattern you can implement within existing toolchains.

Scrape internal DNS metrics from CoreDNS / bind via Prometheus exporters.
Ingest CDN metrics via provider metrics API into Prometheus Pushgateway (or use exporter).
Stream BGP events from a BGP monitor (OpenBMP or BGPStream) and push summarized metrics (withdrawals/min, MOAS count, ROA invalids) into Prometheus.
Use Grafana to build the dashboard and alerting; use Grafana Alerting or Alertmanager for routing alerts to Slack, PagerDuty, and runbook links.

Prometheus alert example (PromQL):

### CDN 5xx POP spike (example)
  sum(rate(cdn_http_responses_total{code=~"5..",pop!=""}[5m])) by (pop)
  /
  sum(rate(cdn_http_responses_total{pop!=""}[5m])) by (pop)
  
  # Alert if a pop's 5xx ratio > 0.01 (1%) and > 5x 1h baseline

Prometheus alert rule YAML (sketch):

groups:
  - name: cdn.rules
    rules:
    - alert: POP5xxSpike
      expr: |
        (sum by(pop)(rate(cdn_http_responses_total{code=~"5.."}[5m]))
        / sum by(pop)(rate(cdn_http_responses_total[5m])))
        > 0.01
      for: 2m
      labels:
        severity: warning
      annotations:
        summary: "CDN 5xx spike in {{ $labels.pop }}"
        runbook: "https://pyramides.cloud/runbooks/cdn-5xx-spike"

Correlating events: playbooks, annotations, and automated mitigations

Alerts without context create noise. Enrich alerts with annotations and automated hints:

Always attach the most recent deploy/infra change to alerts (CI/CD event metadata).
Correlate CDN 5xx spikes with origin RPS and recent deploys to decide rollback versus network mitigation.
For BGP anomalies, open a ticket and enable automated traffic steering if you have multi‑home or multi‑CDN options (e.g., reroute via alternate AS, increase BGP prefixes/policies, or announce MOAS temporarily with careful controls).
DNS issues: if authoritative servers are failing, promote secondary nameservers or switch to an alternate DNS provider with automatic delegation where possible.

Case study: how correlated signals shortened time‑to‑mitigation

In late 2025 a global CDN provider experienced a control plane incident that first showed as a small set of edge 5xx spikes in North America. Teams that had a combined dashboard saw the pattern: rising DNS timeouts from specific resolvers + increased origin latency for a subset of POPs + BGP path churn affecting a handful of peers. By correlating those signals, the team switched affected regions to a secondary CDN POP and rolled back a recent configuration that had increased origin cache‑misses. That cut customer impact from 58 minutes to under 12 minutes.

Operational best practices and 2026 trends to adopt

Multi‑source telemetry: Don’t rely on a single provider’s status page. Aggregate provider metrics, public internet measurements, and your own executors.
RPKI and routing hygiene: By 2026 RPKI adoption is higher, but not universal. Monitor ROA validity for your prefixes and peers; invalidate changes should trigger high‑urgency alerts.
DoH/DoT observability: As resolver privacy increases, instrument and track DoH resolver performance and fallback behavior — some resolver outages manifest only via DoH.
Automated canaries and golden paths: Use global synthetics (with region diversity) as canaries for DNS, CDN, and application health.
Runbook automation: Keep machine‑readable runbooks linked to alerts; automate safe mitigation steps (traffic shifting, DNS delegate swap) but require manual approval for high‑risk changes.

Putting it into practice: a 30‑day plan

Follow these pragmatic steps to deliver an early‑warning dashboard in one month.

Week 1 — Inventory telemetry: identify DNS, CDN, BGP sources, and synthetic probes. Ship key counters to Prometheus or your metrics backend.
Week 2 — Baseline and panels: build the top‑row global health panels and time series for DNS, CDN 5xx and BGP events. Add synthetic checks.
Week 3 — Alerts and runbooks: implement the heuristic alerts above, attach runbooks and deploy alert routing (Slack, PagerDuty) with severity tiers.
Week 4 — Drill and refine: run a tabletop drill simulating correlated DNS+CDN+BGP failure. Tune thresholds, update runbooks, and add richer enrichments (recent deploys, provider incidents).

Common pitfalls and how to avoid them

Too many noisy alerts: use composite alerts that require two signal classes (e.g., DNS timeout + CDN 5xx) for critical pages.
Single‑provider blind spots: add at least two internet measurement sources (e.g., RIPE Atlas + RouteViews) and more than one DNS/CDN provider where feasible.
Alert fatigue on false positives: prioritize high‑confidence, high‑impact alerts for paging; send informational alerts to chat or dashboards only.

Wrap up: building resilience through signal correlation

In 2026 the fastest path to reducing outage blast radius is not faster incident response alone — it’s better detection. Surface the right signals (DNS errors, CDN 5xx spikes, BGP anomalies), correlate them, and automate the first line of mitigation while attaching human context via runbooks. A compact, action‑oriented early‑warning dashboard will shorten mean time to detect and mean time to mitigate, and will protect revenue and reputation when the next cross‑provider incident hits.

"The most valuable telemetry is the one that moves you from reactive firefighting to proactive containment." — Senior SRE, multi‑cloud platform, 2026

Next steps — quick checklist

Instrument DNS servers and push SERVFAIL/timeouts to your metrics backend.
Ingest CDN 5xx, cache miss, and origin latency metrics by POP.
Stream BGP events and ROA validity into your monitoring pipeline.
Create composite alert rules that require correlated signals before paging.
Run a quarterly drill that simulates a multi‑signal outage and refine runbooks.

Call to action

If you want a jumpstart, download our ready‑to‑deploy Prometheus+Grafana dashboard pack and alert rule templates (includes DNS, CDN and BGP rules, plus runbook stubs). Or book a 30‑minute consultation and we’ll review your telemetry posture and help wire the first early‑warning dashboard tailored to your environment.

pyramides

Contributor

Senior editor and content strategist. Writing about technology, design, and the future of digital media. Follow along for deep dives into the industry's moving parts.