How to Migrate to a New CDN Provider with Zero Downtime

In a 2022 global survey, 53% of enterprises reported at least one major CDN-related outage in the previous 12 months — not because their CDN failed, but because a poorly planned migration broke production traffic. When petabytes of content, millions of users, and mission-critical APIs depend on your edge, “we’ll just switch the DNS when it’s ready” becomes a multimillion-dollar risk.

Migrating to a new CDN provider with zero downtime is not only possible — it’s a repeatable, engineered process. The teams that succeed treat CDN migration like a high-stakes product rollout, not a background DevOps task. In this guide, we’ll break down that process into concrete, auditable steps you can follow, whether you’re moving from a legacy CDN or consolidating multiple providers into one modern, cost-efficient platform.

As you read, ask yourself: if your organization had to cut over to a new CDN next month, could you do it without a single dropped request?

Why Enterprises Switch CDN Providers (And Why Downtime Is So Common)

Before diving into the “how,” it’s worth framing the “why.” Gartner and IDC have both noted a steady enterprise trend: companies are moving away from first-generation CDN contracts toward more agile, cost-optimized networks that better match modern workloads — OTT streaming, SaaS, gaming, and high-traffic e-commerce.

Common triggers for a CDN migration include:

• Escalating costs: Per-GB pricing that hasn’t kept pace with market rates, opaque billing, or punitive overage fees.
• Performance inconsistency: Latency spikes in specific regions, or poor video start times and rebuffering rates in key markets.
• Limited flexibility: Slow rule changes, rigid cache behaviors, or brittle configuration tooling that slows down product teams.
• Integration friction: Lack of modern APIs, observability hooks, or support for your CI/CD and infrastructure-as-code stack.
• Contract lock-in: Multi-year commitments that no longer match your usage pattern or growth strategy.

Yet despite good reasons to move, downtime horror stories keep many enterprises stuck on an underperforming CDN:

• DNS cutovers that send traffic to a half-configured edge.
• Cache keys misaligned with origin behavior, exposing stale or private content.
• TLS certificate mistakes leading to browser errors at scale.
• API endpoints forgotten in the migration plan, silently failing after go-live.

Each of these failure modes is preventable with the right plan. As we walk through a zero-downtime migration, keep a list of your own high-risk areas: multi-origin apps, legacy domains, complex cache rules, or mission-critical APIs. Which of those would hurt most if they broke for even five minutes?

Step 1: Define Your Migration Objectives and Risk Profile

This might sound like project-management boilerplate, but the most reliable zero-downtime migrations start with crystal-clear objectives and constraints. The goal is to align stakeholders, define what “success” looks like, and understand your allowable risk envelope.

Clarify success metrics before touching DNS

For a CDN migration, consider success on three dimensions:

• Availability: Zero unplanned downtime and no increase in 4xx/5xx rates during and after cutover.
• Performance: Equal or better core web vitals (LCP, FID/INP, CLS), and at least comparable TTFB and video QoE metrics (startup time, rebuffer ratio).
• Cost: Predictable or reduced CDN spend on a per-GB or per-request basis.

For example, if you’re moving a streaming platform, you may define target streaming startup time and rebuffering thresholds in your key geos. A 2023 Sandvine report found that video streaming already accounts for over 65% of global downstream internet traffic; even minor QoE regressions at scale can translate into churn. Define your acceptable performance delta upfront so you can validate after cutover.

Map stakeholders and ownership

List out everyone who owns a piece of the puzzle:

• Network / infrastructure engineering
• Application / backend teams
• Security and compliance
• Media engineering (for OTT / VOD / live streaming)
• Product and business owners for customer-facing properties
• External partners that depend on your APIs

Define who approves changes, who monitors, and who can roll back. Many “downtime” incidents are actually coordination failures — the right person wasn’t aware or on-call.

Ask yourself: if you had to roll back the migration at 3 a.m. on a Saturday, is there a single runbook everyone trusts and knows how to execute?

Step 2: Audit Your Current CDN Configuration and Traffic

You can’t migrate what you haven’t fully discovered. Underestimating the complexity of your existing CDN edge is one of the primary reasons migrations introduce downtime.

Inventory all domains, subdomains, and endpoints

Start with DNS records and your existing CDN portal to build a comprehensive inventory:

• Primary domains (e.g., www.example.com)
• Static asset domains (e.g., static.example.com, cdn.example.com)
• Media / streaming domains (e.g., vod.example.com, live.example.com)
• API domains (e.g., api.example.com, edge.example.com)
• Legacy or “forgotten” domains still receiving traffic

Correlate this with real traffic logs (ideally 30–90 days) from your current CDN, origin, and observability stack. Pay special attention to legacy URLs, affiliate landing pages, and partner integrations that may not be obvious in your main application codebase.

Document current edge behavior

Next, extract the “business logic” that currently lives at the edge:

• Cache rules and TTLs
• Cache key configuration (query strings, headers, cookies)
• Origin routing and failover logic
• Rewrite and redirect rules (301, 302, 308)
• Security policies (WAF, IP allow/deny lists, geo controls)
• Header manipulation (security headers, custom headers)

For streaming workloads, also capture:

• Tokenized URLs or signed URLs for content protection
• Segment caching strategy (HLS/DASH chunks vs manifests)
• Origin shield or mid-tier caching setups

Where possible, export this configuration as code (JSON, YAML, Terraform, or vendor-specific templates). This becomes your baseline for parity in the new CDN.

Profile your traffic patterns

Analyze request volume, concurrency, and geography. Look for:

• Daily and weekly peak traffic windows
• Regions with the highest latency sensitivity (e.g., mobile-heavy markets)
• Ratio of static vs dynamic vs media traffic
• Average object size distribution

These metrics will directly shape your migration schedule and testing plan. For example, you might choose to first shift low-risk static assets in off-peak hours, then migrate APIs and streaming endpoints with canary routing and intensive monitoring.

As you build this inventory, ask: if we had to reproduce this entire edge configuration in a different provider tomorrow, would anything still be “tribal knowledge” in someone’s head?

Step 3: Design a Zero-Downtime Migration Strategy

With your current state documented, you can now choose a migration strategy that balances risk, speed, and operational overhead. At a high level, you’ll likely choose between a “big bang” cutover (not recommended for large enterprises) and a phased, dual-CDN approach designed for zero downtime.

Why dual-CDN is your safest path

Running your old and new CDN providers in parallel gives you several advantages:

• Progressive traffic shifting (e.g., 1% → 10% → 50% → 100%)
• A real-time, apples-to-apples performance comparison
• Instant rollback if errors spike
• Ability to validate caching behavior, TLS, and headers under production load

Depending on your architecture, you can implement dual-CDN in several ways:

• DNS-based split traffic: Weighted DNS records (e.g., Route 53, NS1) directing a percentage of users to each CDN.
• Application-layer split: Your app selects a CDN domain dynamically (e.g., A/B testing frameworks, config flags).
• Reverse-proxy split: A central proxy (NGINX/Envoy) that forwards to one CDN or another based on routing rules.

DNS-based splitting is usually the most accessible but requires careful coordination with TTLs (time-to-live) to avoid long propagation delays during rollback.

Define your cutover phases

A robust zero-downtime plan commonly uses these phases:

1. Shadow traffic phase: Mirror production traffic to the new CDN without serving end users (via log replay or traffic duplication) to validate behavior and performance.
2. Canary phase (1–5% traffic): Shift a small, low-risk portion of live traffic to the new CDN and monitor closely.
3. Progressive ramp-up: Increase traffic in steps (10%, 25%, 50%, 75%) with health checks and business sign-offs at each stage.
4. Full cutover: Move 100% of traffic once metrics are stable, keeping rollback options available for a defined “watch period.”

Each phase should have clear entry/exit criteria: error budget, latency thresholds, cache-hit ratios, and business KPIs (conversion, streaming abandonment, etc.).

Looking at your current risk profile, where would a phased rollout give you the most confidence — static assets, APIs, or streaming endpoints?

Step 4: Prepare the New CDN Environment for Parity and Improvement

With your strategy in place, it’s time to configure the new CDN — not just to match your existing behavior, but to improve on it where possible without increasing migration risk.

Start with strict configuration parity

Initially, resist the temptation to “optimize everything” while migrating. First, mirror existing behavior:

• Same origins and origin failover rules
• Same cache TTLs and cache keys
• Equivalent redirects and rewrites
• Equivalent security policies (headers, IP rules, auth mechanisms)
• Identical TLS versions, ciphers, and SNI handling

Only once parity is verified under real traffic should you gradually introduce new optimizations such as more aggressive caching, image compression, or advanced routing.

Handle TLS certificates and HSTS carefully

Zero downtime means zero TLS interruptions. Plan for:

• Issuing new certificates covering all relevant domains (including SANs and wildcard certs if needed).
• Ensuring intermediate CA chains are correctly served by the new CDN.
• Preserving or carefully updating HTTP Strict Transport Security (HSTS) headers to avoid locking users to a misconfigured domain.

Browsers can cache HSTS policy for months; a misconfigured HSTS header during migration can cause long-lived access issues. Validate HSTS behavior in staging with real browsers before cutover.

Align caching with origin behavior

Inconsistent cache rules between CDNs is a common source of subtle bugs. Review:

• How your current CDN interprets Cache-Control and Expires headers.
• Any CDN-side overrides that ignore origin headers.
• Edge cases like personalized content with cookies, auth headers, or localization headers.

Confirm that the new CDN handles these patterns identically — especially for authenticated content and signed URLs. A mismatch can either leak private data (over-caching) or hammer your origin (under-caching).

For your own migration, which piece of configuration — TLS, caching, redirects, or security policies — would cause the largest blast radius if implemented incorrectly?

Step 5: Establish Robust Monitoring and Comparison Metrics

You can’t ensure zero downtime if you can’t see what’s happening at the edge in real time. Before you move a single percentage point of traffic, instrumentation must be in place.

Define technical and business SLOs

For each domain or service, define Service Level Objectives (SLOs) across:

• Availability: Error rate thresholds for 4xx/5xx (especially 5xx and 503/504).
• Latency: p50/p95 TTFB and total response time by region and device type.
• Cache efficiency: Cache-hit ratio, origin bandwidth, and request offload.
• Business KPIs: Conversion rate, video completion rate, session duration, or in-game event success rate.

According to Google’s own research, as page load time increases from 1s to 3s, bounce probability increases by 32%. Even if your site remains technically “up,” a poorly monitored migration that hurts performance can cost as much as an outright outage.

Implement side-by-side comparison during dual-CDN

During the dual-CDN phase, you want to compare:

• Latency and TTFB for identical URLs served by each CDN.
• Error rates segmented by CDN provider.
• Cache-hit ratios and origin load per CDN.

If you use synthetic monitoring (e.g., global probes), set up tests that hit the old and new CDN endpoints separately but with the same paths and headers. For real user monitoring (RUM), embed a small beacon that records which CDN edge served the request and the observed performance.

Could your current monitoring stack answer, within 60 seconds, whether the new CDN is performing better or worse in a specific region?

Step 6: Use a Phased, Real-World Testing Plan

With configuration and monitoring in place, you’re ready to test — not just in a lab environment but under realistic, production-like conditions.

Stage 1: Lab and staging validation

In a non-production environment that mirrors your real setup:

• Run integration tests against the new CDN endpoints.
• Validate redirects, rewrites, headers, and caching.
• Confirm authentication flows, tokenized URLs, and DRM for media.
• Use tools like curl, dig, and browser DevTools to inspect responses.

Stage 2: Shadow or replay testing

If your infrastructure supports it, duplicate a slice of real production traffic to the new CDN while responses are still served from the old one. This allows you to:

• Check that origin load from the new CDN is as expected.
• Detect misconfigurations before any real users are affected.
• Fine-tune cache rules and origin shielding.

Stage 3: Low-percentage canary in production

Begin with a very small percentage of users or requests, such as:

• 1–2% of traffic from low-risk geographies.
• Only static assets, keeping HTML and APIs on the old CDN.
• Only logged-out users or specific AB test cohorts.

Monitor for at least one full traffic cycle (e.g., 24 hours) to capture daily patterns. If metrics remain within your defined thresholds, increase traffic gradually.

As you imagine this phased rollout for your own stack, which user cohorts or traffic segments would you choose first to minimize risk while still testing realistically?

Step 7: Execute the DNS and Traffic Cutover Safely

DNS is where many CDN migrations either shine or fail. Done well, users barely notice. Done poorly, you can be stuck in an error state for the length of your previous TTLs.

Control your DNS TTLs ahead of time

Several days before the planned cutover, lower your DNS TTLs for all relevant records (e.g., from 1 hour to 60–120 seconds). This ensures:

• Faster propagation of the new CDN endpoint.
• Faster rollback if a problem emerges.

After the migration stabilizes, you can gradually increase TTLs again to reduce DNS query load.

Use weighted or split-horizon DNS where possible

If your DNS provider supports it, configure:

• Weighted routing: Route a percentage of traffic to old vs new CDN for a domain.
• Geo-based routing: Route specific regions to the new CDN first where you have better performance coverage.

Always start in lower-risk regions or for non-critical parts of your application. Keep a clear mapping of which DNS changes correspond to which migration phase so you can roll them back surgically if needed.

Monitor, decide, and either ratchet forward or rollback

During each DNS change:

• Have an on-call “war room” with engineering, product, and support.
• Watch error rates, latency, and business metrics in near real time.
• Define hard rollback triggers (e.g., error rates above threshold for more than 5–10 minutes).

Document decisions in real time. Within a few cutover steps, you should have enough confidence to move the core domains and APIs.

If you had to flip your primary domain’s DNS in the next hour, do you know exactly which dashboards you’d watch — and what would make you rollback versus push ahead?

Step 8: Validate Performance, Stability, and Cost After Cutover

A lot of teams treat “DNS switched” as the end of the migration. For a zero-downtime, enterprise-grade process, it’s only the start of a critical validation phase.

Compare before-and-after performance data

Using at least 7–14 days of data before and after full cutover, measure:

• Global and regional TTFB changes.
• Core Web Vitals (LCP, INP/FID) in web RUM.
• Streaming QoE metrics like rebuffer ratio and average bitrate for media properties.
• API response latency and error rates.

Adjust caching, routing, or compression settings in the new CDN as needed — but only one major change at a time, so you can attribute effects correctly.

Validate cost and offload improvements

From a financial operations standpoint, evaluate:

• CDN egress cost per GB vs previous provider.
• Cache-hit ratio improvements and resulting origin bandwidth reduction.
• Any reduced need for origin scaling capacity thanks to better offload.

Public data points show that CDN egress pricing varies widely; many legacy contracts still charge significantly above current market rates. A modern provider starting at around $4 per TB (that’s $0.004 per GB) with enterprise-grade performance can translate to six- or seven-figure annual savings for high-traffic platforms.

Debrief with a formal post-migration review

Conduct a retrospective with all stakeholders:

• What worked well in the plan and execution?
• Where were you closest to downtime, and why?
• Which alerts or dashboards were most and least useful?
• What runbooks or playbooks need updating?

Capture these learnings; your next CDN change, multi-CDN expansion, or origin refactor will be smoother because of them.

Looking back over a hypothetical migration, where do you suspect your biggest performance gains — or cost savings — would come from with a better-tuned CDN?

Real-World Patterns: Zero-Downtime CDN Migration in Media, SaaS, and Gaming

Different industries face different edge workloads, but the core principles of zero-downtime migration stay the same. Let’s look at how they play out in three high-stakes sectors.

Media and streaming platforms

Video-centric businesses live and die by streaming quality. Independent benchmark data from services like Conviva and NPAW regularly show that a few hundred milliseconds of extra startup time or small increases in rebuffer ratio can significantly increase viewer abandonment. During a CDN migration, this risk intensifies.

Best practices for streaming-focused migrations include:

• Testing HLS/DASH manifests and DRM-tokenized URLs thoroughly in staging and shadow phases.
• Gradually moving VOD libraries, then live channels once stable.
• Monitoring QoE metrics (start time, rebuffering, average bitrate) per CDN during dual operation.

Modern platforms serving millions of concurrent streams benefit from a CDN that can be flexibly tuned for segment caching, origin shielding, and regional optimizations while still remaining cost efficient.

SaaS and enterprise applications

For SaaS, downtime directly impacts SLAs and customer trust. Many B2B apps have strict uptime commitments, and a poorly handled CDN migration can violate both contractual obligations and brand reputation.

Key focus areas during SaaS CDN migrations:

• Protecting API availability with dual-CDN routing and per-endpoint canaries.
• Ensuring authentication flows (OAuth, SSO, JWT-based sessions) remain intact through caching rules.
• Preserving or improving security posture (WAF, headers, TLS) with no regressions.

Because SaaS teams iterate fast, they also benefit from CDNs that integrate cleanly with infrastructure-as-code, CI/CD pipelines, and observability tools, making configuration changes safe and repeatable.

Online games and real-time services

For gaming companies, CDN usage spans massive static content distribution (game clients, patches, assets) and latency-sensitive services (matchmaking APIs, live events). Any downtime or performance regression can spark community backlash and revenue loss.

When migrating CDNs in gaming contexts, teams typically:

• First move patch and asset delivery, verifying download speeds and regional performance.
• Then handle APIs and real-time services with very conservative canary rollouts.
• Use telemetry from client applications to compare old vs new CDN latency and error rates.

Where does your own business sit on this spectrum — more like streaming, SaaS, or gaming — and which migration risks overlap most with your reality?

How BlazingCDN Fits Into a Zero-Downtime Migration Strategy

Enterprises that decide to move off legacy CDNs often look for two things simultaneously: performance and stability on par with the biggest hyperscale providers, and a pricing model that doesn’t penalize growth. This is exactly the space where BlazingCDN positions itself.

BlazingCDN delivers enterprise-grade reliability and fault tolerance comparable to Amazon CloudFront, but starts at just $4 per TB ($0.004 per GB), making it particularly compelling for bandwidth-intensive workloads like OTT video, high-traffic SaaS, and large game distribution. For organizations pushing terabytes or petabytes monthly, those unit economics quickly translate into meaningful infrastructure savings without sacrificing uptime — backed by a 100% uptime commitment.

Because BlazingCDN emphasizes flexible configuration, real-time analytics, and modern API-driven management, it’s well-suited to the kind of careful, phased migration described in this article. Engineering teams can mirror existing edge logic, roll out traffic gradually, and iterate on optimizations, while finance and operations gain predictable, lower-cost scaling as user demand grows.

Media platforms, software vendors, and game studios that need to balance global reach, performance, and budget constraints already see BlazingCDN as a forward-thinking choice that aligns with both DevOps practices and long-term cost control — not an easy combination to find in older, contract-heavy CDN offerings.

BlazingCDN in Practice: Industry-Specific Migration Advantages

While the core zero-downtime principles apply broadly, BlazingCDN has particular strengths for a few key industries migrating from legacy providers.

Media and streaming

For broadcasters, OTT services, and VOD platforms, predictable streaming quality at scale is non-negotiable. By leveraging advanced caching strategies for segment files, efficient origin shielding, and deep integration with modern observability tools, BlazingCDN helps media companies maintain — or improve — QoE metrics even while transitioning from another CDN. The cost efficiency at $4 per TB provides headroom to grow catalogs and experiment with new formats without being constrained by bandwidth bills.

Teams evaluating a move can explore tailored media workflows and migration-friendly deployment models via **BlazingCDN’s solutions for media companies**, which detail how to handle HLS/DASH, live events, and protection mechanisms in a way that supports phased, zero-downtime rollouts.

SaaS and enterprise software

SaaS vendors migrating off their existing CDN often juggle multiple priorities: preserve SLAs, keep authentication secure, protect multi-tenant boundaries, and maintain fast UI performance worldwide. BlazingCDN’s configurable caching, edge rule management, and strong compatibility with automation stacks help SaaS teams reproduce their current behavior while gaining room to innovate once parity is achieved.

The combination of high reliability, fine-grained control, and aggressive pricing allows SaaS providers to reduce infrastructure costs, scale quickly as customer traffic grows, and reroute or expand into new regions without renegotiating heavyweight contracts.

Gaming and digital distribution

Game companies often manage enormous update payloads and global player bases. A migration that interrupts patch distribution or increases latency during live events is unacceptable. BlazingCDN’s performance characteristics, fault tolerance comparable to CloudFront, and straightforward pricing model support careful, staged migrations of patch traffic, static assets, and real-time services. Game publishers can offload growing bandwidth loads while keeping download times competitive and overall uptime effectively continuous.

Across these industries, the recurring theme is the same: match or exceed existing performance and reliability while significantly reducing the cost per GB and simplifying day-to-day operations.

Key Checks Before You Declare Migration Success

As you approach the final stages of your CDN migration, it’s useful to run through a concise, high-impact checklist. Use this as a final gate before declaring the project complete.

If you can answer “yes” across these dimensions with evidence from your logs and dashboards, your migration has done more than avoid downtime: it has improved your operational baseline for the long term.

Turn Your Next CDN Migration Into a Strategic Upgrade

CDN migrations have a reputation for being risky, painful, and disruptive — but that’s usually a symptom of incomplete planning and opaque legacy contracts, not an inevitable reality. With a structured audit of your current edge, a dual-CDN strategy, disciplined phased rollout, and rigorous monitoring, moving to a new provider can be one of the most impactful infrastructure improvements you make all year, achieved with literally zero downtime.

If your organization is currently held back by rising CDN bills, inconsistent performance, or inflexible configuration tools, this is precisely the moment to evaluate modern alternatives. BlazingCDN offers stability and fault tolerance on par with Amazon CloudFront, a transparent starting cost of $4 per TB, and a feature set designed for fast-growing media, SaaS, and gaming businesses that can’t afford either outages or runaway egress costs.

Use the framework in this article as your internal blueprint: map your edge, define your risk appetite, plan a dual-CDN rollout, and insist on measurable improvements in both performance and cost. Then, start a concrete evaluation with a provider that’s built for this type of migration. Explore features, automation workflows, and performance characteristics in depth at **BlazingCDN’s feature overview**, and when you’re ready, bring your network, DevOps, and product teams into the conversation.

What’s the single biggest obstacle keeping you from moving to a better CDN right now — fear of downtime, migration complexity, or vendor lock-in? Share your perspective with your team, use this guide as a shared reference, and turn your next CDN migration into a controlled, data-driven upgrade instead of a leap of faith.