--- title: What Is a CNAME Record? CNAME vs A Record Explained description: What is a CNAME record? Learn CNAME vs A record differences and how CNAME records connect domains to a CDN. image: https://blog.blazingcdn.com/hubfs/Gemini-Blog/image-Nov-03-2026-11-30-40-2286-PM.jpeg --- [![BlazingCDN](https://blog.blazingcdn.com/hubfs/Logo/blog-logo-w.png)](https://blog.blazingcdn.com?hsLang=en-us) [📘 Learn ▾](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) [🎬 Video & Streaming ▾](https://blog.blazingcdn.com/video-streaming-cdn?hsLang=en-us) [🔴 Live Streaming](https://blog.blazingcdn.com/live-streaming?hsLang=en-us) [📺 VOD & OTT](https://blog.blazingcdn.com/vod-ott?hsLang=en-us) [🎞️ Encoding & Players](https://blog.blazingcdn.com/encoding-players?hsLang=en-us) [🎧 Audio & Podcasts](https://blog.blazingcdn.com/audio-podcasts?hsLang=en-us) [💰 Bandwidth & Costs](https://blog.blazingcdn.com/bandwidth-costs?hsLang=en-us) [🏗️ Infrastructure ▾](https://blog.blazingcdn.com/cdn-infrastructure?hsLang=en-us) [🗄️ Storage & Origin](https://blog.blazingcdn.com/storage-origin?hsLang=en-us) [📦 Large File Delivery](https://blog.blazingcdn.com/large-file-delivery?hsLang=en-us) [💸 Cloud Costs & Egress](https://blog.blazingcdn.com/cloud-costs-egress?hsLang=en-us) [🌐 Networking & ISP](https://blog.blazingcdn.com/networking-isp?hsLang=en-us) [⚙️ DevOps & Cloud Infra](https://blog.blazingcdn.com/devops-cloud-infra?hsLang=en-us) [⚡ Web Performance](https://blog.blazingcdn.com/web-performance?hsLang=en-us) [🏭 Industries ▾](https://blog.blazingcdn.com/cdn-industry-insights?hsLang=en-us) [📺 Media & Broadcasting](https://blog.blazingcdn.com/media-broadcasting?hsLang=en-us) [💾 Software & SaaS](https://blog.blazingcdn.com/software-saas?hsLang=en-us) [📣 AdTech & Advertising](https://blog.blazingcdn.com/adtech-advertising?hsLang=en-us) [🎮 Gaming & Esports](https://blog.blazingcdn.com/gaming-esports?hsLang=en-us) [📱 Mobile Apps & Developers](https://blog.blazingcdn.com/mobile-apps-developers?hsLang=en-us) [🤖 AI & Machine Learning](https://blog.blazingcdn.com/ai-machine-learning?hsLang=en-us) [🏛️ Enterprise & Corporate](https://blog.blazingcdn.com/enterprise-corporate?hsLang=en-us) [📚 E-Learning & EdTech](https://blog.blazingcdn.com/e-learning-edtech?hsLang=en-us) [🏟️ Sports & Live Events](https://blog.blazingcdn.com/sports-live-events?hsLang=en-us) [💰 Pricing & Compare ▾](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) [⚡ Compare](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) [📊 Benchmarks](https://blog.blazingcdn.com/cdn-ratings-and-benchmarks?hsLang=en-us) [🔒 Security ▾](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) [🛠️ Tools](https://blog.blazingcdn.com/cdn-tools?hsLang=en-us) [Get Started](https://blazingcdn.com/sign-up-contact-form/) [Infrastructure](https://blog.blazingcdn.com/en-us/tag/infrastructure) [Infrastructure - Networking & ISP](https://blog.blazingcdn.com/en-us/tag/infrastructure-networking-isp) # What Is a CNAME Record? CNAME vs A Record Explained Vadym Borovskyi Nov 4, 2026, 12:32:42 AM ![](https://blog.blazingcdn.com/hubfs/Gemini-Blog/image-Nov-03-2026-11-30-40-2286-PM.jpeg) A **CNAME record** (canonical name record) is a DNS record that makes one hostname an alias of another. When a resolver looks up the alias, it receives the target hostname and repeats the lookup there until it reaches A or AAAA addresses. A CNAME never holds an IP address, and each alias carries exactly one target. The CNAME record has defined DNS behavior since RFC 1034 in 1987. As of 2026 the core rule is unchanged: a name that holds a CNAME cannot hold any other record type (DNSSEC records excepted). That is why a CNAME cannot sit at a zone apex, which must carry SOA and NS records. ## **How a CNAME record resolves, step by step** A client asks its recursive resolver for the A record of www.example.com. The authoritative nameserver for example.com answers with a CNAME pointing to edge.cdn.example.net. If that nameserver is also authoritative for the target, it includes the target's records in the same response. Otherwise the resolver restarts the query at the target name and keeps following until it reaches address records. Each record in the chain is cached separately under its own TTL. The address a client finally receives is only as fresh as the shortest TTL in the chain. This is the property CDNs rely on. The customer's CNAME can live for an hour while the provider's final A and AAAA records live for 20 to 300 seconds (typical published values), so the provider can steer traffic without the customer touching their zone. ### The latency cost of a CNAME chain: a worked estimate Take a resolver with a cold cache and a chain that spans three zones: the customer zone, the CDN's customer-facing zone, and the CDN's traffic-steering zone. Assume each authoritative round trip costs 20 to 60 ms (an estimate, which depends on resolver placement). A single A record costs one round trip. Two CNAME hops in separate zones cost three, which adds roughly 40 to 120 ms to the first lookup. With a warm cache the extra cost is close to zero, because the resolver answers the whole chain from memory. The cost reappears whenever the shortest TTL expires. A 60-second final TTL on a low-traffic resolver means many lookups pay at least part of the chain again. Keep chains to two hops or fewer, and treat every additional hop as an extra dependency on another set of nameservers. ## **Where a CNAME sits: DNS only, never HTTP** A CNAME acts entirely inside name resolution. The browser still sends the original hostname in the TLS SNI field and in the HTTP Host header. It never sees the target name. This has two practical consequences. The CDN must have your hostname configured, or its edge will not know which origin and cache rules apply. The edge must also present a certificate valid for your hostname, not for its own target hostname. A CNAME that resolves correctly but returns a certificate error or a 404 almost always points to a missing hostname or certificate on the provider side. ## **CNAME vs A record, AAAA and other neighbors** **CNAME vs. A record:** An A record maps a name directly to an IPv4 address and can coexist with MX, TXT and other records at the same name. A CNAME maps a name to another name and must stand alone. Use an A record when you control a stable address. Use a CNAME when someone else controls the addresses and changes them. **CNAME vs. AAAA record:** AAAA is the IPv6 equivalent of an A record. A CNAME delegates both families at once: if the target publishes A and AAAA records, the aliased name becomes dual-stack automatically, with no change in your zone. **CNAME vs. ALIAS, ANAME and flattening:** These are DNS-provider features that resolve the target on the server side and answer with plain A and AAAA records. They work at the apex. However, the ANAME draft never became an RFC, so behavior differs between providers. **CNAME vs. DNAME:** A DNAME (RFC 6672) aliases an entire subtree, such as everything under old.example.com, rather than a single name. It rarely appears in CDN setups. ## **Why can't a CNAME sit on the apex domain?** The apex, such as example.com, must hold SOA and NS records for the zone to function. Because RFC 1034 forbids any other data alongside a CNAME, a CNAME at the apex would conflict with those mandatory records. Most authoritative DNS software rejects that configuration outright, and resolvers that encounter it behave unpredictably. | Apex option | How it works | Trade-off | | --- | --- | --- | | CNAME flattening | The DNS provider follows the target and returns A and AAAA records at the apex | Geo-steering sees the DNS provider's location unless EDNS Client Subnet is forwarded | | ALIAS or ANAME record | A vendor-specific record type that is resolved on the server side | Not standardized, and it ties the apex to one DNS vendor | | Static A and AAAA records to anycast IPs | The CDN publishes fixed anycast addresses | Fully standard, but you must update the records manually if the addresses change | | HTTPS record in AliasMode | A standard apex alias defined in RFC 9460 | Clients do not follow it reliably as of 2026, so A and AAAA fallbacks are still required | | Redirect the apex to www | A small host answers the apex with a 301 redirect to www | Apex visitors pay one extra round trip, and the redirect host must stay available | For most CDN deployments, flattening or anycast A records cover the apex, while the www hostname keeps a plain CNAME. ## **CNAME CDN setup: pointing a site at an edge network** A typical CNAME-based CDN onboarding produces a chain like the one below. The hostnames are placeholders, and the IP addresses come from the documentation ranges. | Name | Type | TTL (seconds) | Value | | --- | --- | --- | --- | | www.example.com | CNAME | 3600 | edge.cdn.example.net | | edge.cdn.example.net | CNAME | 300 | pool-3.cdn.example.net | | pool-3.cdn.example.net | A | 60 | 192.0.2.10 | | pool-3.cdn.example.net | AAAA | 60 | 2001:db8::10 | You control only the first row, and the provider steers traffic by changing the last rows on 60 to 300 second TTLs. Follow this order to cut over safely: 1. Add the hostname at the CDN. 2. Complete certificate validation, which is usually done with a TXT or CNAME challenge record. 3. Lower the existing record's TTL to 300 seconds, one full old-TTL period before the switch. 4. Swap the record for the CNAME. 5. Verify the change by querying the hostname with dig for the CNAME type from two public resolvers, then fetching an asset and checking the CDN's cache status response header. The same CNAME layer is also where multi-CDN splits happen. BlazingCDN includes custom domains and HTTPS certificates on every plan, and it can run as a [**second CDN behind DNS with a weighted traffic split**](https://blazingcdn.com/multi-cdn-integration/), so the split lives in the CNAME layer rather than in your application. ## **Common CNAME misconceptions, corrected** - **"A CNAME redirects the browser."** It does not. The URL bar, the Host header and SNI all keep the original name. Only an HTTP 301 or 302 changes what the user sees. - **"I can add a TXT record next to my www CNAME."** RFC 1034 and RFC 2181 forbid it. Some DNS panels accept the entry anyway, and lookups then break unpredictably. Put domain verification records on a separate label. - **"A CNAME can point to an IP address."** The target must be a hostname. An IP address entered as a CNAME target is treated as a literal name and will not resolve. - **"MX and NS records can target an alias."** RFC 2181 says they must point to names that have A or AAAA records directly. - **"Changing a CNAME takes effect immediately."** Resolvers keep the old answer until its TTL expires, which is why the TTL should be lowered in advance. ## **FAQ: CNAME records, A records and CDN setup** ### What is a CNAME record used for with a CDN? A CNAME record points your hostname, such as www, at a hostname the CDN controls, so the CDN can change edge addresses without any edits to your zone. The provider steers traffic with short TTLs on its own records. You still need the hostname configured at the CDN and a certificate that covers it, because browsers send your original name in SNI. ### Can a CNAME record point to an IP address? No, a CNAME record must point to another hostname, never to an IPv4 or IPv6 address. If you have a fixed address, publish an A or AAAA record instead. An IP address entered as a CNAME target is read as a literal domain name, which does not exist, so lookups for the alias fail with no usable answer. ### Is a CNAME record slower than an A record? A CNAME record is slower only when the resolver cache is cold, because each hop into another zone adds an authoritative round trip, typically estimated at 20 to 60 ms. With a warm cache, the chain is answered from memory at negligible cost. Keeping chains to two hops limits the penalty whenever the shortest TTL expires. ### Can I use a CNAME record on my root domain? Not under the DNS standard, because the root domain must carry SOA and NS records, and a CNAME cannot coexist with any other record type. The usual workarounds are CNAME flattening or ALIAS records from your DNS provider, static anycast A and AAAA records, or redirecting the root domain to a www hostname that holds the CNAME. ## **Audit your CNAME chains before your next CDN change** This week, list every customer-facing hostname you serve and resolve each one with dig from two public resolvers. For each chain, record the hop count, the number of distinct zones involved and the shortest TTL. Flag any chain longer than two hops, any apex that relies on a vendor-specific alias without a documented fallback, and any alias label that also carries TXT or MX records. Ten minutes per domain gives you a dependency map of your DNS that most incident runbooks lack. If that map shows heavy static traffic, such as video, installers or game patches, behind a single CNAME, the [**BlazingCDN features overview**](https://blazingcdn.com/features/) lists what is included on every plan, from custom domains and HTTPS to origin shield and Prometheus metrics. 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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/", "https://www.wikidata.org/wiki/Q141711074" ], "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/what-is-a-cname-record-cname-vs-a-record-explained#article", "@type" : "BlogPosting", "author" : { "@id" : "https://blog.blazingcdn.com/en-us/author/blazingcdn#person", "@type" : "Person", "description" : "Vadym Borovskyi is Chief Product and Marketing Officer at BlazingCDN, where he has led product strategy and growth since 2021. He has more than 11 years of experience in IT product management and B2B marketing. On this blog he writes about CDN pricing and egress costs, video and software delivery, cache configuration, and how teams evaluate and switch CDN providers. 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CNAME vs A Record Explained", "position" : 2 } ] } ``` ```json { "@context" : "https://schema.org", "@id" : "https://blog.blazingcdn.com/en-us/what-is-a-cname-record-cname-vs-a-record-explained#faq", "@type" : "FAQPage", "mainEntity" : [ { "@type" : "Question", "acceptedAnswer" : { "@type" : "Answer", "text" : "A CNAME record points your hostname, such as www, at a hostname the CDN controls, so the CDN can change edge addresses without any edits to your zone. The provider steers traffic with short TTLs on its own records. You still need the hostname configured at the CDN and a certificate that covers it, because browsers send your original name in SNI." }, "name" : "What is a CNAME record used for with a CDN?" }, { "@type" : "Question", "acceptedAnswer" : { "@type" : "Answer", "text" : "No, a CNAME record must point to another hostname, never to an IPv4 or IPv6 address. If you have a fixed address, publish an A or AAAA record instead. An IP address entered as a CNAME target is read as a literal domain name, which does not exist, so lookups for the alias fail with no usable answer." }, "name" : "Can a CNAME record point to an IP address?" }, { "@type" : "Question", "acceptedAnswer" : { "@type" : "Answer", "text" : "A CNAME record is slower only when the resolver cache is cold, because each hop into another zone adds an authoritative round trip, typically estimated at 20 to 60 ms. With a warm cache, the chain is answered from memory at negligible cost. Keeping chains to two hops limits the penalty whenever the shortest TTL expires." }, "name" : "Is a CNAME record slower than an A record?" }, { "@type" : "Question", "acceptedAnswer" : { "@type" : "Answer", "text" : "Not under the DNS standard, because the root domain must carry SOA and NS records, and a CNAME cannot coexist with any other record type. The usual workarounds are CNAME flattening or ALIAS records from your DNS provider, static anycast A and AAAA records, or redirecting the root domain to a www hostname that holds the CNAME." }, "name" : "Can I use a CNAME record on my root domain?" } ] } ```