The Domain Name System (DNS) is a naming database that enables your computer to identify and translate a domain name (e.g., google.com) into an IP address (e.g., 74.125.226.72). DNS zones are specific portions of the DNS managed by a particular organization or administrator. These DNS zones are critical to the DNS as a whole as they simplify the management of DNS records across large, distributed networks. This article is a deep-dive into DNS zones. We explain what DNS zones are, how they work, and why they are important for managing DNS records.
Understanding the Basics of DNS Zones
A DNS zone is a logical entity that refers to a specific domain and its subdomains managed by a single administrator. This concept is quite complex, so let’s break it down.
What Exactly Is a DNS Zone?
A DNS zone is not a material entity. It is a term people use to show that a specific domain—or a part of it (a subdomain/subdomains)—is managed by a single administrator. The administrator can manage DNS records related to their DNS zone by changing, adding, or deleting records.
When you buy a domain, you automatically get control of its DNS zone; you can manage the DNS record of this domain and its subdomains. However, if you want, you can separate out (delegate) some subdomains so that they are managed by someone else. Such a separation means that you create a new DNS zone which contains only the separated subdomain(s).
Why Create a Separate DNS Zone?
The domain owner can separate subdomains and create a new DNS zone for the convenience of managing DNS records. For example, gcore.com has many subdomains, including:
- account.gcore.com
- api.gcore.com
- speedtest.gcore.com
Let’s say a dedicated team is responsible for the speedtest. To allow them autonomy, we can separate speedtest.gcore.com into a separate DNS zone and let the speed test team become the administrator. If they want to move the speed test to different servers, or perhaps link it to a mail server, they can do so themselves without affecting the main site or requiring an external approval process.
FAQs About DNS Zones
What components does a DNS zone include?
A DNS zone includes resource records as its components. One SOA and two NS records are mandatory.
Are top-level domains also DNS zones?
Yes. They simply delegate control over their subdomains (i.e., second-level domains) to the owners of those subdomains.
How can you separate subdomains into a separate DNS zone?
You need to add NS records for the relevant subdomains to the main domain. For more info, check out the DNS Zone Delegation section of this article.
Does each DNS zone correspond to one file with its DNS records?
Yes. One DNS zone corresponds to one file that contains all the DNS records for that specific DNS zone.
Can one DNS zone contain different second-level domains?
No, it can only contain subdomains of the same domain or the domain itself.
Are DNS zones tied to specific DNS servers?
No. One DNS zone corresponds to one file with DNS records. Such a file can be stored on any DNS server. In other words, different files for different DNS zones can be stored on the same server.
What Is a DNS Zone File?
A DNS zone file is usually presented in the form of a plain-text file containing all the important information about a domain name. It contains resource records that are used to map and link domain names to corresponding requests.
A DNS zone file typically contains a Start of Authority (SOA) and NS record and other relevant resource records (RRs,) including—but not limited to—MX, CNAME, A, and TXT records. Let’s take a quick look at what the most common types of records do.
| Resource records in DNS zone files | Function(s) |
| SOA (start of authority) records | Provide the primary source of authority for the domain, including all essential information like the primary DNS server, contact email address, and settings that control how the domain operates |
| NS (nameserver) records | Specify IP addresses of authoritative nameservers and which servers are responsible for providing DNS information about the domain |
| A (address) records | Map the domain names to their associated IP addresses |
| MX (mail exchange) records | Identify the mail servers responsible for handling email for the domain |
| CNAME (canonical name) records | Provide an alias with an actual domain name for existing A records. |
| TXT (text) records | Contain text-based information associated with the domain, such as SPF (Sender Policy Framework) records used for domain ownership validation. |
What Does a DNS Zone File Look Like?
Here is an example of what a DNS zone file for gcore.com could look like in BIND format:
$TTL 1h@ IN SOA dns1.gcore.com. hostmaster.gcore.com. ( 20211209 1d 2h 4w 1h ) IN NS dns1.gcore.com. IN NS dns2.gcore.com. IN MX 10 mail.gcore.com.dns1 IN A 192.168.0.1dns2 IN A 192.168.0.2mail IN A 192.168.0.3web IN A 192.168.0.4www IN CNAME webftp IN CNAME web@ IN TXT "v=spf1 a mx include:spf.gcore.com ~all"spf IN TXT "v=spf1 include:spf.protection.outlook.com include:spf.emailsignatures365.com -all"In this example, the DNS zone file begins with a time-to-live (TTL) directive, which sets the duration for caching DNS records. The “@” symbol represents the root of the domain. Next is the start of authority (SOA) record, which identifies the primary DNS server for the domain, and includes the administrator’s email address. Two nameservers are specified using the IN NS (Internet Nameserver) command, and an MX record is added to designate the mail server, and assign it a priority value of 10.
Several A records are included to define the IP address of various servers. These A records specify the DNS server, mail server and web server IP addresses. The zone file also contains CNAME records, which serve as aliases or alternative names for the web server. This allows different domain names to point to the same web server. Finally, a TXT record is included to specify the Sender Policy Framework (SPF) record for email authentication purposes. This record helps verify that incoming emails originate from authorized servers.
By structuring the DNS zone files like this, administrators can effectively manage the DNS records for their domain. This ensures proper routing of emails, website accessibility, and email authentication.
DNS Zone Delegation
DNS zone delegation is a process that involves dividing a larger DNS zone into smaller zones and assigning them to different DNS servers. This process enables more efficient and localized handling of DNS queries, particularly for larger organizations with multiple subdomains. By delegating zones, the burden on a single server is reduced, leading to improved performance and availability of the overall DNS infrastructure.
Let’s consider a scenario where a large organization manages a primary domain (e.g., example.com) as well as several subdomains (e.g., it.example.com, europe.example.com, us.example.com, etc.) To optimize DNS operations, the organization can delegate each subdomain to separate DNS servers, distributing the workload and enhancing efficiency.
How To Delegate a DNS Zone
To delegate a DNS zone, certain steps need to be followed. The administrator must create NS (nameserver) records for the subdomain. These NS records assign the authoritative servers responsible for handling DNS queries for the subdomain. For example, if the administrator delegates it.example.com subdomain, an NS needs to be added to the example.com zone file. This NS record signifies that the zone file governing the “it” subdomain has the authority to handle all associated DNS queries.
How Do DNS Zones Work?
Imagine that you own the domain example.com. Whenever someone enters example.com into their web browser, their device sends a DNS query to a server requesting the IP address for your website. The server then searches for authoritative DNS zones related to your domain and asks them for the IP address of your website. Once obtained, this IP address is used to establish a connection between the visitor’s device and the server hosting your website.
As the website owner or administrator, DNS zones allow you to manage DNS records for specific parts of your domain. For example, you can have separate DNS zones for mail.example.com or blog.example.com without affecting the records for the entire example.com domain.
To create such a DNS zone, you must specify the subdomain you want to manage in the server’s control panel and create NS records for the subdomain. The NS record can be in the form of an “A” record, which associates the subdomain with an IP address, or an “MX” record, which specifies the mail server for handling email for the subdomain.
What Are DNS Zone Changes?
DNS zone changes are modifications to the DNS information associated with a particular domain. These can include changes to the IP address of the server responsible for hosting the website, adjusting the mail server settings, or adding new servers. These modifications can occur intentionally or accidentally when the domain owner or their authorized representative makes them. However, it’s important to note that DNS zone changes can be maliciously induced by cybercriminals.
Why Track DNS Zone Changes?
Tracking DNS zone changes is crucial for maintaining smooth operation and security of a website. Changes to DNS records can have a significant impact on website functionality. A prime example is the 2021 Facebook outage, during which the website was inaccessible for about seven hours. The outage was caused by the loss of IP routes to the Facebook DNS servers. The resulting revenue loss for Facebook was between $60-100 million.
Furthermore, malicious DNS zone changes can pose serious risks. They can redirect visitors to unauthorized websites, compromising user security. These changes can also open back doors for intrusions into databases and potential breaches of user privacy, which are often triggered by DDoS attacks.
Companies can monitor changes to their domain’s DNS records by actively tracking DNS zone changes. This monitoring allows companies to identify and address any unauthorized or unexpected changes promptly and is essential for safeguarding online presence and protecting user trust.
How To Track DNS Zone Changes
There are five techniques that companies can deploy to track DNS zone changes:
| Tracking Technique | How It Works |
| Zone Change Notification (ZCN) | This feature allows DNS servers to send notifications to other DNS servers when a change occurs in a DNS zone. By enabling ZCN, DNS servers can stay updated with their zone information, and be used for replication of zones as and when needed. |
| DNS Logging | Many DNS servers provide logging capabilities, which monitor DNS queries and updates. These logs provide a record of DNS zone changes, enabling you to identify and troubleshoot issues arising from DNS zone changes. |
| External Monitoring Services | These services use automated tools to monitor DNS answers continuously. They detect changes, such as adding or removing DNS records, and send real-time alerts when DNS zone changes occur. This enables quick responses to potential issues. |
| Dig | This command-line tool allows the user to retrieve DNS information, including DNS records, name servers, and IP addresses. Dig can also be used to track DNS zone changes by comparing DNS queries to DNS servers before and after the zone change, helping the user pinpoint differences. |
| DNS Query Analysis | This technique analyzes DNS queries received by DNS servers to track changes in DNS zones. It provides valuable insights into the domains and subdomains being queried, the types of queries received, and the frequency of queries to specific DNS records. Monitoring these patterns can flag changes to the corresponding DNS zones. |
Why Monitor DNS Zone Changes?
Monitoring DNS zone changes has three main benefits: detecting unauthorized changes immediately, ensuring DNS record accuracy, and improving IT resource management.
Immediate Detection of Unauthorized Changes
Unauthorized changes to DNS zones, whether accidental or malicious, can result in DNS errors, slow query response times, and even domain name resolution failures. Attackers may attempt to modify DNS records to redirect users to phishing sites, intercept traffic, or compromise sensitive information. Actively monitoring DNS zone changes helps mitigate these risks, promptly identifying any unauthorized modifications and enabling DNS administrators to take immediate action.
DNS Record Accuracy
When changes are made to a website or server IP address, corresponding updates to DNS records are necessary to ensure seamless user access to the new server. Incorrect or outdated DNS records can result in website downtime, slow page loading times or even complete website inaccessibility. By monitoring DNS zone changes, companies can verify the accuracy of DNS records, which is crucial for a seamless user experience and for proactively preventing potential problems.
Better IT Resource Management
Regular monitoring of DNS zone changes helps efficiently allocate IT resources. By staying up to date about changes, teams can optimize activities, minimize downtime, and reduce operational costs.
What Is a Reverse Lookup Zone?
A reverse lookup zone enables the identification of domain names associated with specific IP addresses. It works opposite to the more common forward lookup zone, which finds the IP address linked to a domain name.
A reverse lookup zone utilizes special PTR (Pointer) records. It uses the in-addr.appa domain, and IP addresses are arranged from the less specific to the more specific, while the domain names are arranged from the more specific to the less specific. Consider the figure above, for example, the customer’s IP address is 22.64.202.in-addr.appa.
PTRs are always managed in the reverse zone (not forward zone,) like in-addr.arpa or ip6.arpa e.g <octet_2>.<octet_1>.in-addr.arpa. Your ISP must delegate the zone to your NSes. Therefore, when you perform a reverse lookup, the DNS server searches for the PTR record corresponding to the IP address you provide and retrieves the associated domain name.
Reverse lookup zones are particularly valuable in larger networks with numerous IP addresses for troubleshooting network issues. For example, if you detect suspicious activity originating from a particular IP address on your organization’s network, it’s easy to determine visually the domain name associated with that IP address.
Additionally, PTR records are widely used in public networks. You can identify the name associated with an IP address and make a fair assumption about who is responsible for the part of the network that is overloaded or generates malicious traffic. For example:
traceroute to 1.1.1.1 (1.1.1.1), 64 hops max, 52 byte packets 1 192.168.31.1 (192.168.31.1) 10.842 ms 3.846 ms 3.389 ms 2 192.168.178.1 (192.168.178.1) 5.021 ms 5.808 ms 5.727 ms 3 dhcp-077-249-057-001.chello.nl (77.249.57.1) 16.033 ms 13.006 ms 15.976 ms 4 212.142.51.25 (212.142.51.25) 11.897 ms 14.024 ms 12.946 ms 5 asd-tr0021-cr101-be112-2.core.as33915.net (213.51.7.92) 15.071 ms 14.261 ms 15.145 ms 6 nl-ams14a-ri1-ae51-0.core.as9143.net (213.51.64.186) 18.707 ms 16.519 ms 23.037 ms 7 213.46.191.210 (213.46.191.210) 15.810 ms 16.197 ms 16.946 ms 8 172.71.96.2 (172.71.96.2) 15.055 ms 172.70.44.2 (172.70.44.2) 14.475 ms 172.71.180.2 (172.71.180.2) 16.163 ms 9 one.one.one.one (1.1.1.1) 19.013 ms 17.318 ms 21.799 msYou may notice that some addresses don’t have associated PTR records. Usually those addresses are from private IP spaces, and are being used on internal interfaces of the routers. Although we can’t see their name in public, most providers have PTRs for them on their own nameservers, and they are resolved when those nameservers are in use e.g., inside the provider’s network.
It is also worth mentioning that it is not mandatory for a PTR record to correspond to the forward record, and in general it can be an arbitrary domain name. As such, anyone with access to the in-addr.arpa subzone can create PTR for google.com or any other domain name, which in turn can mislead a user or network administrator.
Conclusion
DNS zones play a critical role in the broader DNS system, enabling efficient management of specific subsets of DNS records. Effective DNS management is essential for maintaining website accessibility and email delivery, and supporting various online activities. Poor DNS management can lead to reduced traffic, revenue loss and diminished user trust. Fortunately, companies can optimize DNS management by using appropriate tools and resources, enhancing both efficiency and security in communications between user devices and their chosen servers.
Gcore offers advanced features that empower companies to track DNS zones, detect unauthorized changes, and quickly resolve issues. Gcore’s services include comprehensive tracking, monitoring, and security functionalities. Gcore also provides fast, resilient, and reliable enterprise-grade DNS hosting services. With Gcore, companies can streamline DNS management and ensure a secure, seamless online experience for their users.
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3 use cases for geo-aware routing with Gcore DNS
If your audience is global but you’re serving everyone the same content from the same place, you're likely sacrificing performance and resilience. Gcore DNS (which includes a free-forever plan and enterprise-grade option) offers a straightforward way to change that with geo-aware routing, a feature that lets you return different DNS responses based on where users are coming from.This article breaks down how Gcore's geo-routing works, how to set it up using the GeoDNS preset in dynamic response mode, where it shines, and when you might be better off with a different option. We’ll walk through three hands-on use cases with real config examples, highlight TTL trade-offs, and call out what developers need to know about edge cases like resolver mismatch and caching delays.What is geo-aware DNS routing?Gcore DNS lets you return different IP addresses based on the user’s geographic location. This is configured using dynamic response rules with the GeoDNS preset, which lets you match on continent, country, region, ASN, or IP/CIDR. When a user makes a DNS request, Gcore uses the resolver’s location to decide which record to return.You can control traffic to achieve outcomes like:Directing European users to an EU-based CDN endpointSending users in regions with known service degradation to a fallback instanceBehind the scenes, this is done by setting up metadata pickers and specifying fallback behavior.For step-by-step guidance, see the official docs: Configure geo-balancing with Dynamic response.How to configure GeoDNS in Gcore DNSTo use geo-aware routing in Gcore DNS, you'll configure a dynamic response record set with the GeoDNS preset. This lets you return different IPs based on region, country, ASN, or IP/CIDR metadata.Basic stepsGo to DNS → Zones in the Gcore Customer Portal. (If you don’t have an account, you can sign up free and use Gcore DNS in just a few clicks.)Create or edit a record set (e.g., for app.example.com).Switch to Advanced mode.Enable Dynamic response.Choose the GeoDNS preset.Add responses per region or country.Define a fallback record for unmatched queries.For detailed step-by-step instructions, check out our docs.Once you’ve set this up, your config should look like the examples shown in the use cases below.Common use casesEach use case below includes a real-world scenario and a breakdown of how to configure it in Gcore DNS. These examples assume you're working in the DNS advanced mode zone editor with dynamic response enabled and the GeoDNS preset selected.The term “DNS setup” refers to the configuration you’d enter for a specific hostname in the Gcore DNS UI under advanced mode.1. Content localizationScenario: You're running example.com and want to serve language-optimized infrastructure for European and Asian users. This use case is often used to reduce TTFB, apply region-specific UX, or comply with local UX norms. If you're also localizing content (e.g., currency, language), make sure your app handles that via subdomains or headers in addition to routing.Objective:EU users → eu.example.comAsia users → asia.example.comAll others → global.example.comDNS setup:Host: www.example.comType: A TTL: 120 Dynamic response: Enabled Preset: GeoDNS Europe → 185.22.33.44 # EU-based web server Asia → 103.55.66.77 # Asia-based web server Fallback → 198.18.0.1 # Global web server2. Regional CDN failoverScenario: You’re using two CDN clusters: one in North America, one in Europe. If one cluster is unavailable, you want traffic rerouted regionally without impacting users elsewhere. To make this work reliably, you must enable DNS Healthchecks for each origin so that Gcore DNS can automatically detect outages and filter out unhealthy IPs from responses.Objective:North America → na.cdn.example.comEurope → eu.cdn.example.comEach region has its own fallbackDNS setup:Host: cdn.example.comType: A TTL: 60 Dynamic response: Enabled Preset: GeoDNS North America → 203.0.113.10 # NA CDN IP Backup (NA region only) → 185.22.33.44 # EU CDN as backup for NA Health check → Enabled for 203.0.113.10 with HTTP/TCP probe settingsEurope → 185.22.33.44 # EU CDN IP Backup (EU region only) → 203.0.113.10 # NA CDN as backup for EU Health check → Enabled for 185.22.33.44Note: Multi-level fallback by region isn’t supported inside one rule set—you need to separate them to keep routing decisions clean.3. Traffic steering for complianceScenario: You need to keep EU user data inside the EU for GDPR compliance while routing the rest of the world to lower-cost infrastructure elsewhere. This approach is useful for fintech, healthcare, or regulated SaaS workloads where regulatory compliance is a challenge.Objective:EU users → EU-only backendAll other users → Global backendDNS setup:Host: transactions.example.com Type: A TTL: 300 Dynamic response: Enabled Preset: GeoDNS Europe → 185.10.10.10 # EU regional API node Fallback → 198.51.100.42 # Global API nodeEdge casesGeoDNS works well, but it’s worth keeping in mind a few edge cases and limitations when you get set up.Resolver location ≠ user locationBy default, Gcore uses ECS (EDNS Client Subnet) for precise client subnet geo-balancing. If ECS isn’t present, resolver IP is used, which may skew location (e.g., public resolvers, mobile carriers). ECS usage can be disabled in the ManagedDNS UI if needed.Caching slows failoverEven if your upstream fails, users may have cached the original IP for minutes. Fallback + TTL tuning are key.No sub-regional precisionYou can route by continent, country, or ASN—but not city. City-level precision isn’t currently supported.Gcore delivers simple solutions to big problemsGeo-aware routing is one of those features that quietly solves big problems, especially when your app or CDN runs globally. With Gcore DNS, you don’t need complex infrastructure to start optimizing traffic flow.Geo-aware routing with Gcore DNS is a lightweight way to optimize performance, localize content, or handle regional failover. If you need greater precision, consider pairing GeoDNS with in-app geolocation logic or CDN edge logic. But for many routing use cases, DNS is the simplest and fastest way to go.Get free-forever Gcore DNS with just a few clicks
Flexible DDoS mitigation with BGP Flowspec
For customers who understand their own network traffic patterns, rigid DDoS protection can be more of a limitation than a safeguard. That’s why Gcore supports BGP Flowspec: a flexible, standards-based method for defining granular filters that block or rate-limit malicious traffic in real time…before it reaches your infrastructure.In this article, we’ll walk through:What Flowspec is and how it worksThe specific filters and actions Gcore supportsCommon use cases, with example rule definitionsHow to activate and monitor Flowspec in your environmentWhat is the BGP Flowspec?BGP Flowspec (RFC 8955) extends Border Gateway Protocol to distribute traffic filtering rules alongside routing updates. Instead of static ACLs or reactive blackholing, Flowspec enables near-instantaneous propagation of mitigation rules across networks.BGP tells routers how to reach IP prefixes across the internet. With Flowspec, those same BGP announcements can now carry rules, not just routes. Each rule describes a pattern of traffic (e.g., TCP SYN packets >1000 bytes from a specific subnet) and what action to take (drop, rate-limit, mark, or redirect).What are the benefits of the BGP Flowspec?Most traditional DDoS protection services react to threats after they start, whether by blackholing traffic to a target IP, redirecting flows to a scrubbing center, or applying rigid, static filters. These approaches can block legitimate traffic, introduce latency, or be too slow to respond to fast-evolving attacks.Flowspec offers a more flexible alternative.Proactive mitigation: Instead of waiting for attacks, you can define known-bad traffic patterns ahead of time and block them instantly. Flowspec lets experienced operators prevent incidents before they start.Granular filtering: You’re not limited to blocking by IP or port. With Flowspec, you can match on packet size, TCP flags, ICMP codes, and more, enabling fine-tuned control that traditional ACLs or RTBH don’t support.Edge offloading: Filtering happens directly on Gcore’s routers, offloading your infrastructure and avoiding scrubbing latency.Real-time updates: Changes to rules are distributed across the network via BGP and take effect immediately, faster than manual intervention or standard blackholing.You still have the option to block traffic during an active attack, but with Flowspec, you gain the flexibility to protect services with minimal disruption and greater precision than conventional tools allow.Which parts of the Flowspec does Gcore implement?Gcore supports twelve filter types and four actions of the Flowspec.Supported filter typesGcore supports all 12 standard Flowspec match components.Filter FieldDescriptionDestination prefixTarget subnet (usually your service or app)Source prefixSource of traffic (e.g., attacker IP range)IP protocolTCP, UDP, ICMP, etc.Port / Source portMatch specific client or server portsDestination portMatch destination-side service portsICMP type/codeFilter echo requests, errors, etc.TCP flagsFilter packets by SYN, ACK, RST, FIN, combinationsPacket lengthFilter based on payload sizeDSCPQuality of service code pointFragmentMatch on packet fragmentation characteristicsSupported actionsGcore DDoS Protection supports the following Flowspec actions, which can be triggered when traffic matches a specific filter:ActionDescriptionTraffic-rate (0x8006)Throttle/rate limit traffic by byte-per-second rateredirectRedirect traffic to alternate location (e.g., scrubbing)traffic-markingApply DSCP marks for downstream classificationno-action (drop)Drop packets (rate-limit 0)Rule orderingRFC 5575 defines the implicit order of Flowspec rules. The crucial point is that more specific announcements take preference, not the order in which the rules are propagated.Gcore also respects Flowspec rule ordering per RFC 5575. More specific filters override broader ones. Future support for Flowspec v2 (with explicit ordering) is under consideration, pending vendor adoption.Blackholing and extended blackholing (eBH)Remote-triggered blackhole (RTBH) is a standardized protection method that the client manages via BGP by analyzing traffic, identifying the direction of the attack (i.e., the destination IP address). This method protects against volumetric attacks.Customers using Gcore IP Transit can trigger immediate blackholing for attacked prefixes via BGP, using the well-known blackhole community tag 65000:666. All traffic to that destination IP is dropped at Gcore’s edge.The list of supported BGP communities is available here.BGP extended blackholeExtended blackhole (eBH) allows for more granular blackholing that does not affect legitimate traffic. For customers unable to implement Flowspec directly, Gcore supports eBH. You announce target prefixes with pre-agreed BGP communities, and Gcore translates them into Flowspec mitigations.To configure this option, contact our NOC at noc@gcore.lu.Monitoring and limitationsGcore can support several logging transports, including mail and Slack.If the number of Flowspec prefixes exceeds the configured limit, Gcore DDoS Protection stops accepting new announcements, but BGP sessions and existing prefixes will stay active. Gcore will receive a notification that you reached the limit.How to activateActivation takes just two steps:Define rules on your edge router using Flowspec NLRI formatAnnounce rules via BGP to Gcore’s intermediate control planeThen, Gcore validates and propagates the filters to border routers. Filters are installed on edge devices and take effect immediately.If attack patterns are unknown, you’ll first need to detect anomalies using your existing monitoring stack, then define the appropriate Flowspec rules.Need help activating Flowspec? Get in touch via our 24/7 support channels and our experts will be glad to assist.Set up GRE and benefit from Flowspec today
Tuning Gcore CDN rules for dynamic application data caching
Caching services like content delivery networks (CDNs) can be a solid addition to your web stack. They lower response latency and improve user experience while also helping protect your origin servers through security features like access control lists (ACLs) and traffic filtering. However, if you’re running a highly dynamic web service, a misconfigured CDN might lead to the delivery of stale or, in the worst case, wrong data.If you’re hosting a dynamic web service and want to speed it up, this guide is for you. It explains the common issues dynamic services have with CDNs and how to solve them with Gcore CDN.How does dynamic data differ from static data?There are two main differences between static and dynamic data:Change frequency: Dynamic data changes more often than static data. Some websites stay the same for weeks or months; others change multiple times daily.Personalized responses: Static systems deliver the same response for a given URL path. Dynamic systems, by contrast, can generate different responses for each user, based on parameters like authentication, location, session data, or user preferences.Now, you might ask: Aren’t static websites simply HTML pages while dynamic ones are generated on-the-fly by application servers?It depends.A website consisting only of HTML pages might still be dynamic if the pages are changed frequently, and an application server that generates HTML responses can serve the same HTML forever and always provide everyone with the same content for a URL. The CDN network doesn’t know how you create the HTML. It only sees the finished product and decides how long it should cache it. You need to decide on a case-by-case basis.How do cache rules affect dynamic data?When using a CDN, you have to define rules that govern the caching of your data. If you consider this data dynamic, either because it changes frequently or because you deliver user-specific responses, those rules can drastically impact the user experience, ranging from the delivery of stale data to completely wrong data.Cache expirationFirst, consider cache expiration time. With Gcore CDN, you have two options:Let your origin server control it. This is ideal for dynamic systems using application servers because it gives you precise control without needing to adjust Gcore settings.Let Gcore CDN control it. This works well for static HTTP servers delivering HTML pages that change often. If you can’t modify the server’s cache configuration, using Gcore’s settings is easier.No matter which method you choose, understand what your users consider “stale” and set the expiration time accordingly.Query string handlingNext, decide how Gcore CDN should handle URL query parameters. Ignoring them can improve performance—but for dynamic systems that use query strings for server-side sorting, filtering, or pagination, this can break functionality.For example, a headless CMS might use: https://example.com/api/posts?sort=asc&start=99If the CDN ignores the query string, it will always deliver the cached response, even if new parameters are requested. So, make sure to disable the Ignore query string parameters setting when necessary.Cookie bypassingCookies are often used for session handling. While ignoring cookies can boost performance, doing so risks breaking applications that rely on them.For example: https://example.com/api/users/profileIf this endpoint relies on a session cookie, caching without considering the cookie will serve the same user profile to everyone. Be sure to disable “Ignore cookies” if your server uses them for authentication or personalization.Cache key customizationIf you need more detailed control over the caching, you can modify the cache key generation. This key defines the mapping of a request to a cache entry and allows you to manage the granularity of your caching.The Gcore Customer Portal offers basic customization functionality, and the support team can help with advanced rules. For example, adding the request method (e.g., GET, HEAD, POST, etc.) to your cache key ensures a single URL has a dedicated cache entry for each method instead of using one for all.GraphQL considerationsMost GraphQL implementations only use POST requests and include the GraphQL query in the request body. This means every GraphQL request will use the same URL and the same method, regardless of the query. Gcore CDN doesn’t check the request body when caching, so every query will result in the same cache key and override each other.To make sure the CDN doesn’t break your API, turn off caching for all your GraphQL endpoints.Path-based CDN rules for hybrid contentIf your application serves both static and dynamic content across different paths, Gcore CDN rules offer a powerful way to manage caching more granularly.Using the CDN rules engine, you can create specific rules for individual file paths or extensions. This allows you to apply dynamic-appropriate settings—like disabling caching or respecting cookies—only to dynamic endpoints (e.g., /api/**), while using more aggressive caching for static assets (e.g., /assets/**, /images/**, or /js/**).This path-level control delivers performance gains from CDN caching without compromising the correctness of dynamic content delivery.SummaryUsing a CDN is an easy way to improve your site’s performance, and even dynamic applications can benefit from CDN caching when configured correctly. Check that:Expiration times reflect real-world freshness needsQuery strings and cookies aren’t ignored if they affect the responseCache keys are customized where neededGraphQL endpoints are excluded from cachingCDN rules are used to apply different settings for dynamic and static pathsWith the right setup, you can safely speed up even the most complex applications.Explore our step-by-step guide to setting rules for particular files in Gcore CDN.Discover Gcore CDN
How AI is reshaping the future of interactive streaming
Interactive streaming is entering a new era. Artificial intelligence is changing how live content is created, delivered, and experienced. Advances in real-time avatars, voice synthesis, deepfake rendering, and ultra-low-latency delivery are giving rise to new formats and expectations.Viewers don’t want to be passive audiences anymore. They want to interact, influence, and participate. For platforms that want to lead, the stakes are growing: innovate now, or fall behind.At Gcore, we support this shift with global streaming infrastructure built to handle responsive, AI-driven content at scale. This article explores how real-time interactivity is evolving and how you can prepare for what’s next.A new era for live contentStreaming used to mean watching someone else perform. Today, it’s becoming a conversation between the creator and the viewer. AI tools are making live content more reactive and personalized. A cooking show host can take ingredient requests from the audience and generate live recipes. A language tutor can assess student pronunciation and adjust the lesson plan on the spot. These aren’t speculative use cases—they’re already being piloted.Traditional cameras and presenters are no longer required. Some creators now use entirely digital hosts, powered by motion capture and generative AI. They can stream with multiple personas, switch backgrounds on command, or pause for mid-session translations. This evolution is not about replacing humans but creating new ways to engage that scale across time zones, languages, and platforms.Creating virtual influencersVirtual influencers are digital characters designed to build audiences, promote products, and hold conversations with followers. Unlike human influencers, they don’t get tired, change jobs, or need extensive re-shoots when messaging changes. They’re fully programmable, and the most successful ones are backed by teams of writers, animators, and brand strategists.For example, a skincare company might launch a virtual influencer with a consistent tone, recognizable look, and 24/7 availability. This persona could host product tutorials in the morning, respond to DMs during the day, and livestream reactions to customer feedback at night—all in the local language of the audience.These characters are not limited to influencer marketing. A virtual celebrity might appear as a guest at a live product launch or provide commentary during a sports event. The point is consistency, scalability, and control. Gcore’s global delivery network ensures these digital personas perform without delay, wherever the audience is located.Real-time avatars and AI-generated personasReal-time avatars use motion capture and emotion detection to mimic human behavior with digital models. A fitness instructor can appear as a stylized avatar while tracking their own real movements. A virtual talk show host can gesture, smile, or pause in response to viewer comments. These avatars do more than just look the part—they respond dynamically.AI-generated personas build on this foundation with language generation and decision-making. For instance, an edtech company could deploy a digital tutor that asks learners comprehension questions and adapts its tone based on their engagement level. In entertainment, a music artist might perform live as a virtual character that reflects audience mood through color shifts, dance patterns, or facial expression.These experiences require ultra-low latency. If the avatar lags, the illusion collapses. Gcore’s infrastructure supports the real-time input-output loop needed to make digital characters feel present and responsive.Deepfake technology for creative storytellingDeepfakes are often associated with misinformation, but the same tools can be used to build engaging, high-integrity content. The technology enables face-swapping, voice cloning, and character animation, all of which are powerful in live formats.A museum might use deepfake avatars of historical figures for interactive educational sessions. Visitors could ask questions, and Abraham Lincoln or Golda Meir might respond with historically grounded answers in real time. A brand could create a fictional spokesperson who evolves over time, appearing in product demos, ads, and livestreams. Deepfake technology also allows multilingual content without re-recording—the speaker’s lip movements and tone are modified to match each language.These applications raise legitimate ethical questions. Gcore’s streaming infrastructure includes controls to ensure the source and integrity of AI-generated content are traceable and secure. We provide the technical foundation that enables deepfake use cases without compromising trust.Synthetic voices and personalized audioAudio is often overlooked in discussions about AI streaming, but it’s just as important as video. Synthetic voices today can express subtle emotions and match speaking styles. They can whisper, shout, pause for dramatic effect, and even mimic regional accents.Let’s consider a news platform that offers interactive daily briefings. Viewers choose their preferred language, delivery style (casual, serious, humorous), and even the voice profile. The AI generates a personalized broadcast on the fly. In gaming, synthetic characters can offer encouragement, warn about strategy mistakes, or narrate progress—all without human voice actors.Gcore’s streaming infrastructure ensures that synthetic voice outputs are tightly synchronized with video, so users don’t experience out-of-sync dialogue or lag during back-and-forth exchanges.Increasing interactivity through feedback and participationInteractivity in streaming now goes far beyond comments or emoji reactions. It includes live polls that influence story outcomes, branching narratives based on audience behavior, and user-generated content layered into the broadcast.For example, a live talent show might allow viewers to suggest challenges mid-broadcast. An online classroom could let students vote on the next topic. A product launch might include a real-time Q&A where the host pulls questions from chat and answers them in the moment.All of these use cases rely on real-time data processing, behavior tracking, and adaptive rendering. Gcore’s platform handles the underlying complexity so that creators can focus on building experiences, not infrastructure.Why low latency is criticalInteractive content only works if it feels immediate. A delay of even a second can break immersion, especially when users are trying to influence the outcome or receive a response. Low latency is essential for real-time gaming, sports, interviews, and educational formats.A live trivia game with hundreds of participants won’t retain users if there’s a lag between the question appearing and the timer starting. A remote surgery training session won’t work if the avatar’s responses trail behind the mentor’s instructions. In each of these cases, timing is everything.Gcore Video Streaming minimizes buffering, supports high-resolution streams, and synchronizes data flows to keep participants engaged. Our infrastructure is built to support high-throughput, globally distributed audiences with the responsiveness that interactive formats demand.Preparing for what’s nextAI-generated content is no longer a novelty. It’s becoming a standard feature of modern streaming strategies. Whether you’re building a platform that features virtual influencers, immersive avatars, or interactive educational streams, the foundation matters. That foundation is infrastructure.If you’re planning the next generation of live content, we’re ready to help you bring it to life. At Gcore, we provide the performance, scale, and security to launch these experiences with confidence. Our streaming solutions are designed to support real-time content generation, audience interaction, and global delivery without compromise.Want to see interactive streaming in action? Learn how fan.at used Gcore Video Streaming to deliver ultra-low-latency streams and boost fan engagement with real-time features.Read the case study
What are captions and subtitles, and how do they work?
Subtitles and captions are essential to consuming video content today. But how do they work behind the scenes?Creating subtitles and captions involves a five-step process to ensure that your video’s spoken and auditory content is accurately and effectively conveyed. The five steps are transcription, correction, synchronization/spotting, translation, and simulation/display on screen.The whole process is usually managed using specialized subtitle or caption creator software.In this blog, we explain the five steps in more detail, what the end user sees, and how to choose the right caption/subtitle service for your needs.Step 1: TranscriptionSpoken content is transformed into a text-based format. Formats are different ways to implement the textual elements, depending on technical needs.Transcription creates the raw materials that will be refined in stages 2–4.Step 2: CorrectionCorrection enhances readability by improving the textual flow. Punctuation, grammar, and sentence structure are adjusted so that the user’s reading experience is seamless and doesn’t detract from the content.Step 3: Synchronization/spottingNext, the text and audio are aligned precisely. Each caption or subtitle’s timing is adjusted so it appears and disappears at the correct moment.Step 4: TranslationTranslation is required for content intended for consumption in multiple languages. During this stage, it’s important to consider format requirements and character limitations. For example, a caption that fits on two lines in English might require three in Spanish, and so in Spanish, one caption becomes two. As a result, additional synchronization might be necessary.Step 5: Simulation/display on screenFinally, the captions or subtitles need to be integrated onto the end user’s screen. Formatting issues might arise at this stage, requiring tweaks for an optimal user experience.How does the end user see subtitles and captions?After the technical process of creating captions and subtitles, the next step is understanding how these elements appear to the end user. The type of captions you choose can greatly impact the user experience, especially when considering accessibility, engagement, and clarity. Below, we break down the different options available and how they serve different viewing scenarios.Open captions: These are always visible to viewers and are a fixed part of the video. They’re popular, for example, for video installations in museums and employee training videos—cases where maximum accessibility is the key consideration when it comes to captions and/or subtitles.Closed captions: Viewers can turn these on or off based on preference. For instance, an online course might offer this feature, allowing learners to choose how to consume the content. Students could opt temporarily to turn on closed captions to note the spelling of a new term introduced during the course.Real-time captions: These are great for live events like webinars, where the text appears almost simultaneously as the words are spoken. They keep the audience engaged in real time without missing out on crucial points. For example, ambient noise like chatter in a sports bar might obscure commentary on a live TV basketball game. Real-time captions allow viewers to benefit from near-live commentary regardless of the bar’s noise levels or if the TV’s sound is muted.Burned-in subtitles: These are etched onto the video and cannot be turned off. A promotional video targeting a multilingual audience might use this feature so that everyone understands the message, regardless of their language preference.What to look for in captioning and subtitling servicesTo deliver high-quality captions and subtitles, it's important to choose a provider that offers key features for accuracy, efficiency, and audience engagement.Original language transcription: Accurate documentation of every spoken word in your video for unrivaled accuracy.Tailored translation: Localized content that integrates translations with cultural relevance, increasing resonance with diverse audiences.Alignment synchronization: Time-annotated subtitles, matching words perfectly to the on-screen action.Automatic SRT file generation: A simplified subtitling and captioning process through effortless file creation for a better user experience.Transform your videos with cutting-edge captions and subtitles from GcoreNo matter your video content needs, it’s essential to be aware of the best type of captions and subtitles for your audience’s needs. Choosing the right format ensures a smoother viewing experience, better accessibility, and stronger engagement across every platform.Gcore Video Streaming offers subtitles and closed captions to enhance users’ experience. Each feature within the subtitling and captioning toolkit is crafted to expand your video content’s reach and impact, catering to a multitude of use cases. Embedding captions is quick and easy, and AI-automated speech recognition also saves you time and money.Try Gcore's automated subtitle and caption solution for free
Why captions and subtitles are essential for video engagement
From TikToks on silent commutes to training videos in noisy offices, silent viewing is now standard. Captions and subtitles aren’t just accessibility features anymore. They’re essential for user engagement, global reach, and video performance.This article explores why captions and subtitles matter and how they boost engagement with your videos, providing a better user experience for your audience. If you want to know how captions and subtitles work, we’ve got an article for that too.How subtitles and captions improve your video performanceSubtitles are now widely used across platforms and age groups. For many younger viewers, reading along while watching is second nature, especially on social media. For others, subtitles are a practical solution: watching videos in public spaces, scrolling during breaks, or learning on the go—all without needing sound.Captions offer tangible benefits across four key areas:Engagement and comprehension: Improve clarity in movies, boost understanding in online courses, and increase focus in business content.Accessibility and inclusion: Make content available to hard-of-hearing users and break language barriers for global audiences.SEO and discoverability: Search engines can crawl subtitle text, making your video content more findable, even when autoplayed without sound.Silent usability: Your content works in all environments, from crowded trains to quiet offices.Captions have shifted from niche to norm, helping creators reach more people, boost retention, and deliver clearer messages.Common challenges and their solutionsImplementing captions at scale poses three major challenges: cost, delay, and accuracy. Here's why these challenges exist and how Gcore Video Streaming can help you overcome them at the click of a button.CostInvesting in high-quality transcriptions can be a financial burden, especially for smaller players in online education. Specialized expertise is required for accurate educational content, and human oversight adds ongoing labor costs. Transcription is a recurring expense that grows with multiple languages or regulatory compliance.Gcore scalable AI-powered transcription services reduce reliance on costly manual processes, offering affordable, multi-language support with built-in compliance features, making transcription cost-effective for all budgets.Delay/latencyIn live events, even slight delays in captioning can disengage audiences. For example, in a Formula One race, missing real-time commentary on pit stops or track conditions can leave viewers confused or frustrated. Lagging captions fail to keep pace with the action, breaking immersion.Real-time AI ASR (automatic speech recognition) from Gcore minimizes captioning delay, so that live captions sync perfectly with events, keeping viewers fully engaged without lag.AccuracyA small text error in captions can distort the message and harm reputation. Errors in MOOCs or corporate webinars risk undermining credibility and discouraging future participation. Precision is critical to maintain trust and clarity.Gcore leverages advanced AI models fine-tuned for domain-specific vocabulary and includes automated quality checks, drastically reducing errors and preserving message integrity across all video content.Enhance your video content with Gcore AI-powered caption and subtitles toolsCaptions are now a strategic content layer, not just an accessibility checkbox. With video now the dominant format across marketing, education, and entertainment, it's critical to implement captions efficiently, affordably, and at scale.Gcore’s AI-powered Video Streaming lets you generate accurate, real-time captions across multiple languages with minimal developer effort. Built-in AI ASR (automatic speech recognition) means your captions stay synchronized even during fast-paced live events. Whether you’re running an LMS, hosting global events, or publishing OTT content, Gcore Video Streaming helps you scale captions with speed and precision.Request a demo of Gcore AI ASR
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