The complete IT admin playbook to fixing slow DNS lookup

When network performance starts to lag, it’s common to overlook the small background processes that actually trigger the delay. Tackling these specific IT issues early prevents minor lags from turning into widespread connectivity complaints. Even during a major software deployment, a simple DNS bottleneck can make the most robust applications feel broken.

The first step to resolving these issues is pinpointing exactly where the DNS lookup is stalling. In this blog, we’ll show you how to measure DNS latency accurately and outline the practical steps you can take to fix it.

Practical considerations when investigating slow DNS lookups

Before assuming a broader network or application problem, it’s important to understand where DNS latency typically occurs and how it appears in real-world environments. In corporate networks, DNS delays are often internal and layered, with several small inefficiencies adding up to noticeable slowness.

DNS lookup delays usually come from three main internal areas, each affecting performance in a different way:

• Endpoint configuration can introduce delays when DNS servers are misordered, unreachable, or overridden by VPN or security software. Windows clients, for example, may wait several hundred milliseconds before failing over to the next resolver when a preferred DNS server does not respond, which quickly adds up during repeated lookups.
• Resolver behavior plays a major role when internal DNS servers are overloaded, poorly cached, or configured with low TTL values. Ineffective caching forces repeated upstream queries instead of serving responses locally. Google’s research shows that effective DNS caching can reduce lookup times by 30–80%.
• Network topology can slow DNS resolution when queries take indirect or unnecessary routes. Split-DNS setups, traffic that loops between sites (hairpin routing), or DNS requests passing through multiple proxies all add extra network hops, increasing the time it takes to resolve a name.

» Check out the common DNS errors and how to fix them

Measuring and benchmarking DNS lookup time

DNS lookup time should be measured where users actually experience it, not only on servers or network devices.

Industry benchmarks provide useful context:

• DNS lookups under 50 ms are usually not noticeable to users.
• 50–100 ms is generally acceptable.
• Anything over 150 ms starts to impact perceived performance.

Google performance research shows DNS delays can make up 20–30% of total page load time on first visits. The most telling signal is comparison: if DNS is slow but TCP and TLS setup are fast, DNS is the limiting factor. Repeated spikes or high variability matter more than a single slow average.

How to fix slow DNS lookups

Slow DNS lookups usually happen because your computer is asking the wrong DNS server, waiting too long for one that does not respond, or using outdated cached information. Here are two practical methods to fix this.

Method 1: Manual DNS fix on a single computer

This method is best when you are working on one personal computer and have access to network settings. It is visual and doesn’t require any scripting.

Steps:

1. Click the Wi-Fi or Ethernet icon in the taskbar, and select the Settings icon

2. Select Network and Internet, and click Properties on your active connection

3. Scroll to IP Assignment and click Edit

4. Change the setting from Automatic to Manual

5. Turn IPv4 on

6. Enter the DNS servers:

• Preferred DNS: 1.1.1.1
• Alternate DNS: 8.8.8.8

7. Save the changes and reconnect to the network

Why this works: Most computers default to DNS servers run by your Internet Service Provider. These are often slower and can get “clogged” when busy. By switching to a public provider like Cloudflare or Google, you are using a global “fast lane.” These providers have massive networks with servers located closer to you, meaning your requests take a shorter path and get answered almost instantly from their huge memory banks.

Method 2: PowerShell

PowerShell is the preferred method in corporate or managed environments where you need to diagnose or fix DNS issues across many computers, often without touching network settings manually.

Steps:

1. Search PowerShell in the search bar and click “run as administrator”

2. Check which DNS servers your computer is using by copying and pasting the command in PowerShell: Get-DnsClientServerAddress

Take note: This will show the list of DNS servers your computer is trying first. It helps identify if there are misordered or outdated servers, such as old VPN resolvers, that can cause delays.

3. Measure how long a DNS lookup takes. If the response is slow, it indicates that DNS, rather than your internet or the website, is the source of delay. Copy and paste the following command in PowerShell: Measure-Command { Resolve-DnsName www.google.com }

4. Clear cached DNS records by copying and pasting: Clear-DnsClientCache into PowerShell. This removes old DNS information your computer has stored. It is completely safe and does not delete files, passwords, or personal data.

Managing dozens or hundreds of computers is hard enough without having to chase down DNS issues one by one. Atera’s RMM platform helps you get ahead of the curve by spotting those errors before users even start complaining about “slow internet.”

The platform manages all your endpoints in real-time, so you’ll see right away if a resolver is misconfigured or if a group of devices is still trying to hit an old VPN server. You get a clear look at the patterns instead of having to guess what’s going wrong.

When you need to fix something, the AI Copilot makes it seamless. You can just type, “write a script to reset DNS settings for everyone,” and generate the PowerShell script for you to deploy remotely through the RMM platform.

Optional advanced tips for faster DNS

For users managing multiple computers, offices, or networks, there are additional steps you can take to improve DNS performance. These are more advanced than the basic manual or PowerShell methods, but they can make a significant difference in speed and reliability.

Switching DNS providers

If your current DNS server is slow, overloaded, or far away, changing to a well-peered public or private DNS provider can improve performance. Popular options include:

• Google Public DNS: 8.8.8.8 (preferred) and 8.8.4.4 (alternate)
• Cloudflare DNS: 1.1.1.1 (preferred) and 1.0.0.1 (alternate)

Why it works: Many ISP-provided DNS servers are centralized and may experience congestion, adding 200–500 milliseconds per lookup. Public DNS providers often use anycast networks, which place servers physically closer to your location for faster responses.

How to test: Before and after switching, measure DNS response times using:

• nslookup in Command Prompt

• dig on Linux or macOS

• Browser DevTools (Timing > DNS lookup)

This ensures that any speed improvements are real and consistent across devices.

» Make sure you understand the difference between PowerShell and Command Prompt

Adjusting DNS caching and TTL values

DNS caching determines how long your computer or server remembers a website’s address before asking the DNS server again. TTL controls how long this information is stored at different layers of the network.

Properly managing caching and TTL reduces repeated lookups and speeds up access without causing errors.

• Check that DNS caching is enabled on your computer: On Windows, the DNS Client service caches records automatically. Make sure this service is running and not being cleared by scripts or security software.
• Align application caching with system settings: Web browsers, Java programs, and containerized applications may use their own DNS cache. For example, older Java versions would store DNS entries indefinitely unless configured. Adjust application caches to match your system or authoritative DNS TTL values to prevent stale routing while still reducing repeated lookups.
• Adjust TTL at the authoritative DNS level if you manage a server: Longer TTLs, such as 5–60 minutes (300–3600 seconds), reduce repeated queries and lighten network load. Shorter TTLs, such as 30–120 seconds, allow updates, failovers, or migrations to happen quickly without disrupting users.

Practical impact: Cloudflare reports that optimized TTL strategies can reduce recursive DNS traffic by up to 50% without affecting site updates. This is especially useful in multi-site offices, SaaS-heavy environments, or microservices architectures.

7 other ways to fix slow DNS lookups

The methods above cover the two most common fixes, but slow DNS lookups can stem from a range of other causes — from hijacked settings to outdated firmware. Here are a few more ways to track down and resolve the issue.

1. Enable DNS over HTTPS/TLS (DoH/DoT)

Encrypts and speeds up DNS queries by using modern secure resolvers built into most browsers and operating systems today.

2. Check for malware or hijacked DNS settings

Malicious software can silently reroute your DNS queries, making lookups seem slow when the real issue is redirection.

3. Set up a local caching resolver

Tools like dnsmasq or a local Windows DNS forwarder store recent lookups on-site, cutting down repeated trips to external servers.

4. Audit VPN split-tunneling configuration

DNS queries routed unnecessarily through a VPN tunnel add latency — check your split-tunnel rules to keep local traffic local.

5. Review IPv6/IPv4 fallback settings

A misconfigured IPv6 setup can cause delays as devices wait on failed IPv6 lookups before falling back to IPv4.

6. Update router firmware and network drivers

Outdated firmware or NIC drivers can slow down how quickly DNS requests are processed and sent out.

7. Deploy fixes fleet-wide with RMM scripting

For MSPs managing hundreds of endpoints, manually applying DNS fixes one device at a time isn’t practical — RMM tools let you push cache flushes, resolver changes, or adapter resets across your entire fleet at once.

Eliminate DNS bottlenecks for good

Fixing one slow computer is easy. The challenge is maintaining performance across an entire enterprise IT environment. Atera’s RMM platform gives you real-time visibility into every device on the network, so you can spot a failing resolver before “the internet is slow” tickets start coming in.

Instead of running from desk to desk, you can use the AI Copilot to handle the heavy lifting. You can simply ask it to write a script that updates DNS settings for every workstation in a specific department and push it out through the RMM platform. This shifts your workflow from reacting to problems to managing your entire enterprise IT environment with a few clicks, keeping the network fast without the manual grind.

» Interested in taking control of your environment? Try Atera for free