--- title: "Anycast vs DNS Routing: How a CDN Picks the PoP" description: "Anycast CDN vs DNS routing CDN: see how CDNs select the nearest PoP with edge routing for faster content delivery." image: https://blog.blazingcdn.com/hubfs/Gemini-Blog/image-Sep-20-2026-07-30-23-3710-AM.jpeg --- [![BlazingCDN](https://blog.blazingcdn.com/hubfs/Logo/blog-logo-w.png)](https://blog.blazingcdn.com?hsLang=en-us) [๐Ÿ“˜Learn โ–พ](https://blog.blazingcdn.com/cdn-learn?hsLang=en-us) [CDN Fundamentals](https://blog.blazingcdn.com/cdn-fundamentals?hsLang=en-us) [By Content Type](https://blog.blazingcdn.com/by-content-type?hsLang=en-us) [Advanced Concepts](https://blog.blazingcdn.com/advanced-concepts?hsLang=en-us) [Glossary](https://blog.blazingcdn.com/glossary?hsLang=en-us) [โšก Web Performance](https://blog.blazingcdn.com/web-performance?hsLang=en-us) [๐ŸŽฌVideo & Streaming โ–พ](https://blog.blazingcdn.com/video-streaming-cdn?hsLang=en-us) [๐Ÿ”ด Live Streaming](https://blog.blazingcdn.com/live-streaming?hsLang=en-us) [๐Ÿ“บ VOD & OTT](https://blog.blazingcdn.com/vod-ott?hsLang=en-us) [๐Ÿ’ฐ Bandwidth & Costs](https://blog.blazingcdn.com/bandwidth-costs?hsLang=en-us) [๐Ÿญ Other Industries โ–พ](https://blog.blazingcdn.com/cdn-industry-insights?hsLang=en-us) [๐Ÿ“บ Media & Broadcasting](https://blog.blazingcdn.com/media-broadcasting?hsLang=en-us) [๐Ÿ’พ Software & SaaS](https://blog.blazingcdn.com/software-saas?hsLang=en-us) [๐Ÿ—๏ธ DevOps & Cloud Infra](https://blog.blazingcdn.com/devops-cloud-infra?hsLang=en-us) [๐Ÿ“š AdTech & Advertising](https://blog.blazingcdn.com/adtech-advertising?hsLang=en-us) [๐ŸŽฎ Gaming & Esports](https://blog.blazingcdn.com/gaming-esports?hsLang=en-us) [๐Ÿ“ฑ Mobile Apps & Developers](https://blog.blazingcdn.com/mobile-apps-developers?hsLang=en-us) [๐Ÿค– AI & Machine Learning](https://blog.blazingcdn.com/ai-machine-learning?hsLang=en-us) [๐Ÿ›๏ธ Enterprise & Corporate](https://blog.blazingcdn.com/enterprise-corporate?hsLang=en-us) [๐Ÿ“š E-Learning & EdTech](https://blog.blazingcdn.com/e-learning-edtech?hsLang=en-us) [๐ŸŸ๏ธ Sports & Live Events](https://blog.blazingcdn.com/sports-live-events?hsLang=en-us) [๐Ÿ’ฐ Pricing & Costs โ–พ](https://blog.blazingcdn.com/cdn-pricing-and-cdn-costs?hsLang=en-us) [Provider Pricing](https://blog.blazingcdn.com/provider-pricing?hsLang=en-us) [Cost Optimization](https://blog.blazingcdn.com/cost-optimization?hsLang=en-us) [Decision Support](https://blog.blazingcdn.com/decision-support?hsLang=en-us) [โšกCompare โ–พ](https://blog.blazingcdn.com/cdn-comparison?hsLang=en-us) [Provider Comparisons](https://blog.blazingcdn.com/provider-comparisons?hsLang=en-us) [Strategy Comparisons](https://blog.blazingcdn.com/strategy-comparisons?hsLang=en-us) [Ratings & Benchmarks](https://blog.blazingcdn.com/cdn-ratings-and-benchmarks?hsLang=en-us) [๐Ÿ“Š Benchmarks](https://blog.blazingcdn.com/cdn-ratings-and-benchmarks?hsLang=en-us) [๐Ÿ”’ Security โ–พ](https://blog.blazingcdn.com/cdn-security?hsLang=en-us) [Attack Protection](https://blog.blazingcdn.com/attack-protection?hsLang=en-us) [Encryption & Access](https://blog.blazingcdn.com/encryption-access?hsLang=en-us) [Video & DRM Security](https://blog.blazingcdn.com/video-drm-security?hsLang=en-us) [๐Ÿ“ Case Studies](https://blog.blazingcdn.com/case-studies?hsLang=en-us) [๐Ÿ”Œ Integrations](https://blog.blazingcdn.com/integrations?hsLang=en-us) [๐Ÿ› ๏ธ Tools](https://blog.blazingcdn.com/cdn-tools?hsLang=en-us) [Get Started](https://blazingcdn.com/sign-up-contact-form/) [Learn](https://blog.blazingcdn.com/en-us/tag/learn) [Compare](https://blog.blazingcdn.com/en-us/tag/compare) [Learn - CDN Fundamentals](https://blog.blazingcdn.com/en-us/tag/learn-cdn-fundamentals) [Compare - Strategy Comparisons](https://blog.blazingcdn.com/en-us/tag/compare-strategy-comparisons) # Anycast vs DNS Routing: How a CDN Picks the PoP Vadym Borovskyi Sep 20, 2026, 9:33:54โ€ฏAM ![](https://blog.blazingcdn.com/hubfs/Gemini-Blog/image-Sep-20-2026-07-30-23-3710-AM.jpeg) Evaluated February 2026. Two mechanisms decide which edge serves a request, and they fail on completely different timescales. An anycast CDN hands the decision to BGP, which reconverges in roughly 2โ€“30 seconds after a route withdrawal. DNS routing hands the decision to resolvers, whose caches push practical failover to 30โ€“300 seconds even when the authoritative TTL is 20 seconds. Anycast wins on failover speed and cold-start latency; DNS steering wins on granularity, per-user control, and multi-CDN. Most large 2026 deployments run both: DNS selects the region, anycast selects the machine inside it. If you are short-listing vendors, the routing model is not a footnote in the architecture diagram. It determines how fast you recover from a bad edge, whether you can drain 20% of a location, and how badly your latency numbers degrade for users behind public resolvers. ![Diagram comparing anycast CDN routing and DNS routing for CDN edge selection](https://blog.blazingcdn.com/hs-fs/hubfs/Gemini%20INBlog%20Pictures/image-Sep-20-2026-07-30-39-5520-AM.jpeg?width=1280&height=720&name=image-Sep-20-2026-07-30-39-5520-AM.jpeg) ## **Anycast CDN vs DNS routing: how each one actually picks an edge** ### Anycast CDN routing: BGP decides, and BGP does not measure latency An anycast CDN announces the same prefix from many locations. The client never chooses; every transit network and peer between the client and the CDN runs its own best-path selection over local preference, AS path length, MED, and IGP cost. Latency is not an input to that algorithm. It is a frequent side effect, not a guarantee. That is why anycast produces excellent medians and ugly tails. Hot-potato routing inside a transit provider can hand a subscriber in one metro to an edge two countries away because that is where the provider's cheapest handoff sits. You cannot fix it with a config change; you fix it with peering, prefix deaggregation, or BGP communities that influence upstream selection. ### DNS routing CDN behavior: resolver geography, ECS, and the TTL floor A DNS routing CDN answers a query with a hostname or address chosen by an authoritative server that sees, at best, the recursive resolver's address. EDNS Client Subnet (RFC 7871) improves this by passing a truncated client prefix, commonly an IPv4 /24. Coverage is partial: several major public resolvers send client subnet data, at least one large privacy-focused resolver deliberately does not, and corporate forwarders often strip it. The control is real. You can weight a region at 5% increments, pin a customer to a specific stack, steer by ASN, or shift traffic between two CDNs on a dashboard. The cost is a resolution chain that adds a measurable first-request penalty on cold cache, typically 20โ€“80 ms across two or three CNAME hops in 2026 measurements, plus a failover floor set by health-check interval, TTL, resolver cache, and client-side caching you do not control. ## **Evaluation criteria for CDN PoP selection** Six criteria separate the models in an evaluation. Assumptions: global consumer traffic, mixed HTTP/2 and HTTP/3, origin in one region, a compliance requirement that some traffic stays in-region. - **Cold-start latency:** time from first DNS query to first byte, not steady-state RTT. - **Failover time:** measured from edge failure to the client's first successful request, not from the vendor's alert. - **Load control granularity:** can you drain a fraction of a location, or only all of it? - **Session stability:** what happens to long-lived HTTP/2 and WebSocket connections during a routing change. - **Multi-CDN compatibility:** whether a second vendor can be inserted without re-architecting. - **Observability:** whether you can prove which edge served a request, from the outside. | Routing model | Typical failover (2026) | Control granularity | Dominant failure mode | | --- | --- | --- | --- | | Anycast (BGP) | 2โ€“30 s (route withdrawal plus reconvergence) | Coarse: announce or withdraw | Third-party path policy sends a region to a distant edge; overload concentrates on one site | | DNS steering with client subnet | 30โ€“120 s | Fine: per subnet, per ASN, weighted | Resolvers that strip or ignore client subnet fall back to resolver geography | | DNS steering without client subnet | 30โ€“300 s | Fine, but aimed at the wrong target | Users mapped to the resolver's location, not their own | | Hybrid: DNS to region, anycast inside | 2โ€“30 s intra-region, 30โ€“120 s cross-region | Regional weights plus fast local recovery | Two control planes, two sets of health data, harder root-cause analysis | | Client-side steering (multi-CDN switcher) | Seconds, per session | Per player or per request | Only works for apps you control; useless for third-party embeds | The single most important conclusion: anycast recovers roughly an order of magnitude faster than DNS routing, but only DNS routing lets you move a defined fraction of traffic on purpose. ## **Vendor comparison: who routes how in 2026** | Vendor | List price per TB (2026, estimate) | Published uptime SLA | Edge routing model | | --- | --- | --- | --- | | BlazingCDN | $5/TB entry, down to $2.50/TB at volume | Not published | Confirm the model per account during evaluation; it is not spelled out in public docs | | Bunny.net, CDN77, Gcore, Medianova | ~$5โ€“$40/TB, region dependent | 99.9%โ€“100%, tier dependent | Mixed anycast and DNS steering; verify per product | | Fastly | ~$120/TB list, far lower on commit | 100% (enterprise) | Anycast | | Amazon CloudFront | ~$85/TB at 10 TB, ~$20โ€“$40/TB at high volume | 99.9% monthly | DNS-based steering by default, optional anycast address ranges since 2024 | | Cloudflare | Not metered per TB on most plans; enterprise is custom | 100% (enterprise) | Anycast, every address announced from every site | | Akamai | Contract only | Contract-negotiated | DNS mapping with short TTLs, refreshed from internal path measurements | The takeaway from the table: pure-anycast vendors give you the fastest recovery with the least steering control, while DNS-mapping vendors give you the opposite, and price per TB varies by more than an order of magnitude across the same routing models. **BlazingCDN.** Priced as progressive pay-as-you-go tiers rather than per-region rate cards, with NVMe SSD edge storage and roughly one-hour onboarding for a standard HTTP pull configuration. Pricing starts at $5 per TB and falls to $2.50 per TB at volume (as of October 2026), which matters most to enterprises moving hundreds of terabytes of software builds, game patches, or video. Honest limitation: the routing mechanics are not documented publicly at the level Cloudflare or Fastly publish, so put "describe the edge selection and failover path" in your RFP and validate it in the bake-off below rather than assuming. **Cloudflare.** The reference implementation of anycast at scale, with the deepest peering and the most public writing about how it behaves. Limitation: steering granularity is coarse by design, and bandwidth economics are opaque enough that year-three costs are hard to model. **Fastly.** Anycast plus a genuinely programmable edge; the best fit when routing decisions need to happen in code after the connection lands. Limitation: list pricing is high, so the economics only work with a committed volume deal. **Amazon CloudFront.** DNS-based selection with tight integration into the rest of the AWS control plane, and an optional anycast address range for customers who need stable IPs for allowlisting. Limitation: on-demand list pricing is the most expensive per TB in this set, and its published monthly SLA is 99.9%. **Akamai.** Decades of investment in measurement-driven DNS mapping; still the strongest option when you need per-network steering in places where BGP paths are poor. Limitation: procurement and configuration cycles are long, and nothing is self-serve. **Bunny.net, CDN77, Gcore, Medianova.** Cost-competitive alternatives in the same league on price, with capable routing for mainstream web and video workloads. Limitation: routing behavior differs between their products, and published SLA terms vary by tier, so read the specific contract rather than the marketing page. ## **Worked cost math at two volumes** Assumptions: 2026 published list pricing, North America and Europe delivery, no private discount applied, cache hit ratio irrelevant to egress billing. BlazingCDN prices egress as pay-as-you-go tiers: as of October 2026, pricing starts at $5 per TB and falls to $2.50 per TB at volume, so 100 TB costs $415. For comparison, Amazon CloudFront's published on-demand tiers work out to roughly $6,965 for the same 100 TB in North America and Europe before any private pricing agreement. At 2,000 TB per month the gap narrows in percentage terms because CloudFront's list tiers fall toward $20โ€“$30 per TB, but the absolute monthly difference still runs into five figures. Negotiated enterprise contracts compress this; the routing model you choose does not change the bill, so evaluate routing and price as separate line items. If you want the full per-TB breakdown alongside routing behavior, the [**CDN comparison of price per TB and edge routing**](https://blazingcdn.com/cdn-comparison/) is the faster starting point than assembling six rate cards by hand. ## **Recommendation matrix: which routing model fits which workload** | Workload | Best fit | Why | | --- | --- | --- | | API and SaaS, short requests | Anycast CDN | No cold DNS penalty, fastest recovery, sessions are short enough that mid-flight route changes are cheap | | Live streaming, large audiences | Hybrid or client-side steering | Need to shift measured fractions of viewers between vendors during an event | | Game patches and software builds | Anycast with cost-optimized vendor | Throughput and price per TB dominate; a 50 ms routing difference is noise on a 4 GB download | | Data residency requirements | DNS routing | Only DNS steering lets you assert which region answers, since BGP paths are not yours to control | | WebSocket or long-lived connections | DNS routing, or anycast with reconnect logic | Anycast route changes drop in-flight sessions; the client must reconnect cleanly | The pattern across the matrix: pick anycast when recovery speed matters more than placement control, and DNS routing when you must be able to say exactly where a given user's traffic went. ## **FAQ: anycast CDN and DNS routing for CDN PoP selection** ### Is anycast routing faster than DNS-based CDN routing? Anycast is usually faster on first request because it removes the DNS resolution chain, which costs roughly 20โ€“80 ms on a cold cache in 2026 measurements. Steady-state latency depends on peering quality, not the routing model. A well-peered DNS-mapped network can beat a poorly peered anycast network in any given metro. ### How long does DNS-based CDN failover take? Plan for 30โ€“300 seconds end to end. The chain is health-check detection interval, authoritative record change, TTL expiry at the recursive resolver, and finally client or runtime caching that may ignore the TTL entirely. Anycast failover skips all four steps and completes in BGP reconvergence time, typically 2โ€“30 seconds. ### Does EDNS Client Subnet fix DNS routing accuracy? EDNS Client Subnet (RFC 7871) narrows the error substantially but does not eliminate it. Coverage is incomplete: some large public resolvers do not send client subnet data on privacy grounds, and enterprise forwarders often strip the option. Traffic from those paths is still mapped by resolver location, which can be hundreds of kilometres from the user. ### Can multi-CDN work with an anycast CDN? Yes, but the switching layer has to sit above the anycast layer. You either steer with DNS above two anycast vendors, accepting DNS failover timing, or you select CDN hostnames inside your own application or video player, which gives per-session switching but only for clients you control. ### How do you test which edge location a CDN selected? Resolve the hostname from multiple networks, then read the vendor's edge identification response header on an HTTP HEAD request and compare it against the TCP or QUIC handshake round-trip time. Run a traceroute from the same vantage point to see which transit network made the path decision. Repeat during peak hours, when routing and capacity pressure both change. ## **Run this bake-off before you sign** Two weeks, two vendors, four measurements. First, resolve the test hostname from at least 30 networks across your top five markets and record the answers plus TTLs. Second, measure handshake round-trip time at p50, p95, and p99 per market, not just the average. Third, capture the edge identity header for every request so you can prove which site served it. Fourth, ask each vendor to drain one location during a scheduled window and time the gap from last error to first successful request. Whoever refuses step four has answered the routing question for you. 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The CDN for video and large traffic Their monthly bill vs ours - 20 TBFastly $2,087**$92.50** - 50 TBCDN77 $990**$215** - 200 TBCloudFront $11,965**$765** Published list prices, Aug 2026 [Calculate your cost](https://blazingcdn.com/cdn-cost-calculator/?utm_source=blog&utm_medium=sidebar&utm_campaign=blog_sidebar&utm_content=compare_calc) ## Related posts [![](https://blog.blazingcdn.com/hubfs/Gemini-Blog/image-Oct-09-2026-07-30-19-6786-AM.jpeg)](https://blog.blazingcdn.com/en-us/what-is-h-264-avc-the-codec-behind-most-online-video?hsLang=en-us) Learn ### [What Is H.264 (AVC)? The Codec Behind Most Online Video](https://blog.blazingcdn.com/en-us/what-is-h-264-avc-the-codec-behind-most-online-video?hsLang=en-us) H.264, also called Advanced Video Coding (AVC) or MPEG-4 Part 10, is a block-based video compression standard published ... Oct 9, 2026, 9:32:23โ€ฏAM [Read more](https://blog.blazingcdn.com/en-us/what-is-h-264-avc-the-codec-behind-most-online-video?hsLang=en-us) [![](https://blog.blazingcdn.com/hubfs/Gemini-Blog/image-Oct-09-2026-07-00-57-1652-AM.jpeg)](https://blog.blazingcdn.com/en-us/best-cdn-static-websites-static-file-delivery?hsLang=en-us) Compare ### [Best CDN for Static Sites and File Delivery: 2026 Comparison](https://blog.blazingcdn.com/en-us/best-cdn-static-websites-static-file-delivery?hsLang=en-us) At 100 TB a month, the published price gap between options for a CDN for static content is more than 16 times: ... 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All rights reserved. ```json { "@context" : "https://schema.org", "@id" : "https://blazingcdn.com/#organization", "@type" : "Organization", "description" : "High-volume CDN for video, live streaming, OTT/IPTV, software, games, SaaS and large-file delivery.", "logo" : { "@id" : "https://blazingcdn.com/#logo", "@type" : "ImageObject", "height" : 560, "url" : "https://blazingcdn.com/wp-content/uploads/2024/08/logo-560-560.png", "width" : 560 }, "name" : "BlazingCDN", "sameAs" : [ "https://www.linkedin.com/company/blazingcdn", "https://x.com/BlazingCdn", "https://www.reddit.com/r/BlazingCDN/" ], "url" : "https://blazingcdn.com/" } ``` ```json { "@context" : "https://schema.org", "@id" : "https://blog.blazingcdn.com/#website", "@type" : "WebSite", "inLanguage" : "en-US", "name" : "BlazingCDN Blog", "publisher" : { "@id" : "https://blazingcdn.com/#organization" }, "url" : "https://blog.blazingcdn.com/" } ``` ```json { "@context" : "https://schema.org", "@id" : "https://blog.blazingcdn.com/en-us/anycast-vs-dns-routing-how-a-cdn-picks-the-pop#article", "@type" : "BlogPosting", "author" : { "@type" : "Person", "name" : "Vadym Borovskyi" }, "dateModified" : "2026-10-07T15:42:15Z", "datePublished" : "2026-09-20T07:33:54Z", "description" : "Anycast CDN vs DNS routing CDN: see how CDNs select the nearest PoP with edge routing for faster content delivery.", "headline" : "Anycast vs DNS Routing: How a CDN Picks the PoP", "image" : "https://143144902.fs1.hubspotusercontent-eu1.net/hubfs/143144902/Gemini-Blog/image-Sep-20-2026-07-30-23-3710-AM.jpeg", "inLanguage" : "en-us", "isPartOf" : { "@id" : "https://blog.blazingcdn.com/#website" }, "mainEntityOfPage" : { "@id" : "https://blog.blazingcdn.com/en-us/anycast-vs-dns-routing-how-a-cdn-picks-the-pop", "@type" : "WebPage" }, "publisher" : { "@id" : "https://blazingcdn.com/#organization" }, "wordCount" : 2034 } ``` ```json { "@context" : "https://schema.org", "@id" : "https://blog.blazingcdn.com/en-us/anycast-vs-dns-routing-how-a-cdn-picks-the-pop#breadcrumb", "@type" : "BreadcrumbList", "itemListElement" : [ { "@type" : "ListItem", "item" : "https://blog.blazingcdn.com/en-us", "name" : "Blog", "position" : 1 }, { "@type" : "ListItem", "item" : "https://blog.blazingcdn.com/en-us/anycast-vs-dns-routing-how-a-cdn-picks-the-pop", "name" : "Anycast vs DNS Routing: How a CDN Picks the PoP", "position" : 2 } ] } ``` ```json { "@context" : "https://schema.org", "@id" : "https://blog.blazingcdn.com/en-us/anycast-vs-dns-routing-how-a-cdn-picks-the-pop#faq", "@type" : "FAQPage", "mainEntity" : [ { "@type" : "Question", "acceptedAnswer" : { "@type" : "Answer", "text" : "Anycast is usually faster on first request because it removes the DNS resolution chain, which costs roughly 20โ€“80 ms on a cold cache in 2026 measurements. Steady-state latency depends on peering quality, not the routing model. A well-peered DNS-mapped network can beat a poorly peered anycast network in any given metro." }, "name" : "Is anycast routing faster than DNS-based CDN routing?" }, { "@type" : "Question", "acceptedAnswer" : { "@type" : "Answer", "text" : "Plan for 30โ€“300 seconds end to end. The chain is health-check detection interval, authoritative record change, TTL expiry at the recursive resolver, and finally client or runtime caching that may ignore the TTL entirely. Anycast failover skips all four steps and completes in BGP reconvergence time, typically 2โ€“30 seconds." }, "name" : "How long does DNS-based CDN failover take?" }, { "@type" : "Question", "acceptedAnswer" : { "@type" : "Answer", "text" : "EDNS Client Subnet (RFC 7871) narrows the error substantially but does not eliminate it. Coverage is incomplete: some large public resolvers do not send client subnet data on privacy grounds, and enterprise forwarders often strip the option. Traffic from those paths is still mapped by resolver location, which can be hundreds of kilometres from the user." }, "name" : "Does EDNS Client Subnet fix DNS routing accuracy?" }, { "@type" : "Question", "acceptedAnswer" : { "@type" : "Answer", "text" : "Yes, but the switching layer has to sit above the anycast layer. You either steer with DNS above two anycast vendors, accepting DNS failover timing, or you select CDN hostnames inside your own application or video player, which gives per-session switching but only for clients you control." }, "name" : "Can multi-CDN work with an anycast CDN?" }, { "@type" : "Question", "acceptedAnswer" : { "@type" : "Answer", "text" : "Resolve the hostname from multiple networks, then read the vendor's edge identification response header on an HTTP HEAD request and compare it against the TCP or QUIC handshake round-trip time. Run a traceroute from the same vantage point to see which transit network made the path decision. Repeat during peak hours, when routing and capacity pressure both change." }, "name" : "How do you test which edge location a CDN selected?" } ] } ```