How to optimize DNS for reliable business operations

The ABCs of DNS 

When you enter the URL of a website in your browser, e.g., TechTarget.com, your computer sends out a query to find the corresponding IP address. The query's first stop is the DNS recursive resolver, typically provided by your ISP.

This resolver issues a series of requests to find the IP address, starting from the root server. Thirteen sets of root servers are available worldwide, each identified by letters A through M. Root servers don't really know the IP address you are looking for, but they can direct requests in the right direction through the appropriate top-level domain (TLD) server -- in our case, the TLD responsible for .com domains.

The TLD then refers the query to the authoritative nameserver specifically delegated for the second-level domain (SLD) -- where the actual domain resides. This information is returned to the DNS resolver and then received by the browser. This process -- known as DNS resolution -- typically takes milliseconds.

If you've visited the specific site before, your browser will most likely have it cached locally in the stub resolver located in the DNS client running on your machine's OS. If not found in the cache, it will check the local hosts file for a manual mapping. If it is found, then the entire external resolution process will be skipped.

DNS also plays a role in email delivery. When you send an email, your mail server uses DNS to look up the mail exchanger records for the recipient's domain. The MX records tell your server where to deliver the emails.

The need for DNS optimization

Unreliable DNS can severely affect productivity. Increased page load times result in higher bounce rates, which reduce conversions and SEO, ultimately resulting in revenue loss for businesses. For employees, DNS failures disrupt access, leading to an increase in IT support tickets and other operational issues.

It's no surprise that attackers set their sights on DNS. A 2025 Forrester study reported that 95% of companies faced DNS-related attacks within the past year, with incursions costing companies an average of $1.1 million per attack. The October 2025 incident that targeted AWS' Northern Virginia region's DNS management resulted in the provider being down for 15 hours, affecting various high-profile sites.

Companies can employ the strategies below to optimize DNS performance and ensure resiliency. 

Multi-region and multi-cloud deployment

Design your DNS architecture to run across multiple cloud providers and regions from the start. This approach will eliminate dependencies, maintain high availability, prevent vendor lock-in and enable compliance with data sovereignty laws.

Consider multi-provider synchronization, where primary authoritative DNS zones are hosted in one cloud and replicas (secondary zones) in others (e.g., Azure DNS, Google Cloud DNS or Cloudflare). This setup can be synchronized with DNS tools for consistency.

Geographical traffic distribution can be handled by Anycast routing, natively supported by most DNS providers. This steers incoming traffic to specific regions within cloud environments. For example, if users in Asia query your domain, Anycast may route to the nearest point-of-presence, which could be Google Cloud's Asia-South PoP (with the lowest latency).

If that region or provider fails, the Border Gateway Protocol reroutes to the next closest -- for example, AWS Asia-Pacific. Optionally, improve regional intelligence by using global server load balancing. Taking this step gives businesses near-100% uptime and prevents severe disruptions that affect revenue.

Load balancing and automatic failover

Implement load balancing with an active-active configuration that efficiently distributes traffic across a pool of healthy and active servers. No switch-over is required; if one server goes down, the others absorb the load seamlessly.

Pair load balancing with a DNS failover strategy. DNS-based failovers continuously check the health of application endpoints in a primary region, probing network reachability, response codes or even for specific content.

Configure address and canonical names with failover policies that dictate switching these records to a secondary region if necessary. If an endpoint in a primary region fails, the DNS service detects this anomaly and updates the DNS record. Hence, traffic and other active processes are redirected from the IP address of an unhealthy server or data center to the IP address of a preconfigured standby server with data (zone) replication, typically located in a different geographical location.

Validate periodically to ensure readiness for incident response. Load balancing and automatic failover complement each other: load balancing for day-to-day efficiency and failover for resilience during problems. AWS Route 53 offers native failover routing with health checks, while Cloudflare provides advanced load balancing with steering options.

How to manage DNS performance

Organizations can take the following steps to boost the performance of their DNS:

1. Choose a fast, reliable provider

Rather than stick to DNS servers provided by your ISP, which are often slow and unreliable, switch to a high-performance public or managed provider. Examples include Cloudflare (1.1.1.1), Google Public DNS (8.8.8.8) and Quad9 (9.9.9.9). Run a DNS benchmark for your location to know what's best.

2. Understand the time to live value

DNS is incredibly efficient, but caching can make it even faster. When a DNS resolver finds the IP address for a domain, it stores this information for a certain period known as the time to live (TTL). When a query is made for the same domain within this TTL period, the resolver will respond immediately from its cache, bypassing the entire lookup process.

It's important to be aware of trade-offs, however. A lower TTL value -- such as 60 seconds -- permits faster DNS propagation, speeding up failover events or migrations. This is because the client devices will query for updated records more frequently. But this increases query volume and can cause latency. A higher TTL value -- such as one to 24 hours -- will reduce the number of queries to authoritative servers, thus reducing the load and improving speed.

3. Integrate with content delivery networks

Consider using a CDN as an authoritative DNS provider. DNS queries are distributed and resolved through the CDN's global network of edge servers. Assets are cached at the edge, thus reducing loads. This approach is recommended for applications with media-heavy content. Edge caching dramatically lowers delivery times and bandwidth costs.

How to secure DNS

Because DNS is bidirectional, it carries data and can't be turned off, making it ripe for abuse. As a result, adversaries are constantly developing new ways to exploit it. Below are some methods to protect it.

Use DNSSEC to validate DNS data integrity

By default, DNS queries are funneled through UDP port 53, which is in plain text and unencrypted, making it a prime target for malicious actors.

Common attacks include DNS spoofing and DNS cache poisoning:

• DNS spoofing. Hackers sniff and impersonate your DNS server, intercept requests and respond with another IP address.
• DNS cache poisoning. Bad actors insert false information into a DNS resolver's cache, redirecting users to malicious websites without their knowledge.

DNS Security Extensions add a layer of cryptographic signatures to the DNS data, ensuring the information received is authentic and hasn't been tampered with.

DDoS mitigation and network traffic filtering

Imagine a scenario in which the root name servers are targeted by a DDoS attack. If these servers get taken down or become slow to respond, the entire chain of DNS queries could be delayed or fail.

While such a coordinated attack could, in theory, delay global DNS resolution, this scenario is unlikely to occur given the servers' massive Anycast distribution across hundreds of independent instances worldwide.

Actual DDoS threats involve DNS amplification or reflection attacks on authoritative or recursive servers, in which malicious actors spoof the victim's IP to obtain oversized responses from open resolvers, thus multiplying the traffic volume exponentially.

To combat these attacks, employ a layered approach:

1. Start with anycast absorption. This tactic will spread attack traffic and prevent a single point of overload.
2. Implement rate limiting to control the number of requests the DNS server can process within a period of time. A CDN adds an extra layer of security.
3. Deploy traffic filtering to intercept DNS queries and evaluate them against threat intelligence to check if the destination site is safe before anything malicious can occur.
4. Enforce policies to block inappropriate and unproductive sites. DNS filtering options range from public or free DNS resolvers, like Cloudflare 1.1.1.1 and Cisco Umbrella -- previously known as OpenDNS -- to enterprise-grade platforms such as Cloudflare Gateway.

Access controls and monitoring

Implement strict access controls and continuously monitor and detect misconfigurations, as well as identify suspicious activity, such as unauthorized changes. Optimize DNS by deploying role-based access control on your authoritative DNS servers or DNS provider to restrict access to only designated sysadmins, developers or IT executives. Access should be unique, with multi-factor authentication enforced.

Wisdom Ekpotu is a DevOps engineer and technical writer focused on building infrastructure with cloud-native technologies.