Changing DNS: What It Fixes — and What It Doesn’t
A website refuses to load.
You search online and find the usual advice:
“Change your DNS to Google or Cloudflare.”
Sometimes that works immediately.
Websites begin resolving again and everything appears normal.
Other times it changes absolutely nothing.
That is because DNS is important, but it is only one part of the connection.
Changing DNS can solve problems involving:
name resolution
It does not magically repair:
weak Wi-Fi
packet loss
broken Ethernet
slow broadband
overloaded routers
failing VPNs
broken websites
The useful question is:
Is DNS actually the part that is failing?
What Does DNS Do?
DNS stands for:
Domain Name System
Think of it as the internet’s directory.
You type:
hgmssp.com
Your computer needs an IP address to contact the server.
DNS performs that lookup.
Google describes DNS as the internet’s “phone book”: browsers and applications use DNS queries to translate human-friendly names into network addresses. (developers.google.com)
Without working DNS, your internet connection can technically still be active while websites fail to open by name.
What Changing DNS Can Fix
1. Your Current DNS Resolver Is Failing
Suppose your ISP’s DNS server is:
unavailable
timing out
misconfigured
You may see symptoms such as:
websites saying server not found
some apps failing to connect
repeated DNS errors
internet appearing connected but browsing failing
Switching temporarily to another resolver may restore name resolution.
That is a legitimate DNS fix.
2. A Particular Domain Is Resolving Incorrectly
A DNS server can occasionally return:
stale information
incorrect cached records
failed resolution
Testing another resolver can help establish whether the problem is specific to the resolver you are using.
For example:
nslookup example.com
can show which DNS server answered and what address it returned.
Microsoft’s current DNS troubleshooting guidance focuses on identifying whether resolution itself is failing before changing unrelated network components. (learn.microsoft.com)
3. Cached DNS Information Is Wrong
Windows maintains a local DNS cache.
If the cached answer is stale or incorrect, you can clear it.
Open Command Prompt and run:
ipconfig /flushdns
Then retry the site.
This does not change your DNS provider.
It simply clears Windows’ locally cached DNS responses so it can request fresh information.
4. Your DNS Provider Is Very Slow
DNS lookups can affect how quickly a website starts loading.
A slow resolver can create a delay before the browser begins contacting the destination.
A faster DNS service may therefore improve the feeling of responsiveness.
But this needs context.
DNS affects:
finding the server
not:
the actual download speed once the connection is established.
If your broadband connection is 30 Mbps, switching DNS does not suddenly turn it into 500 Mbps.
5. Your Existing DNS Provider Is Blocking a Domain
Some DNS services deliberately filter:
malware
adult content
advertising
unwanted categories
Business networks may also use protective DNS to block malicious destinations.
The NCSC’s Protective DNS model works exactly this way: the resolver prevents access to domains known to be malicious. (ncsc.gov.uk)
So if a website works after changing DNS, do not immediately conclude:
“The old DNS was broken.”
It may have been intentionally blocking the destination.
On a business network, bypassing that control can weaken security.
What Changing DNS Does NOT Fix
Slow Wi-Fi
If the laptop has:
weak signal
interference
poor access-point placement
changing DNS will not repair the wireless connection.
You might get slightly faster initial name lookups.
The unstable Wi-Fi remains unstable.
Packet Loss
If Teams calls sound robotic because packets are being lost, DNS is not the problem after the session has already resolved the service endpoints.
Investigate:
Wi-Fi
router
ISP
congestion
network equipment
not the DNS resolver.
High Latency
Changing DNS may reduce lookup delay.
It will not fundamentally change the latency of:
PC → router → ISP → remote service
Once the destination has been resolved, DNS is largely out of that data path.
Poor Download Speed
DNS does not increase:
Ethernet link speed
broadband sync
Wi-Fi bandwidth
If a speed test is capped at 95 Mbps because Ethernet negotiated at 100 Mbps, changing DNS will achieve nothing.
Fix the Ethernet link.
A Broken Website
If one website’s server is:
offline
overloaded
misconfigured
a new DNS resolver generally cannot repair it.
It may point you to the same broken server more efficiently.
That is still broken.
A Faulty Router
If the router keeps:
dropping packets
rebooting
losing WAN connectivity
changing DNS may temporarily make troubleshooting more confusing.
Fix the actual network fault.
A Bad Ethernet Cable
A damaged cable does not care which DNS server you use.
If the Ethernet link repeatedly drops or negotiates at the wrong speed, replace or test the cable and port.
DNS vs Internet Connectivity: The Quick Test
A useful diagnostic approach is to separate:
Can I reach the network?
from:
Can I resolve names?
For example, if IP connectivity works but name resolution fails, DNS becomes interesting.
Run:
nslookup microsoft.com
If the lookup fails while the connection itself remains healthy, DNS deserves investigation.
If DNS resolves successfully but websites still fail, look elsewhere.
Changing DNS on Windows 11
Windows 11 allows DNS configuration through:
Settings > Network & internet
Select:
Wi-Fi
or:
Ethernet
Then edit:
DNS server assignment
Microsoft’s current network settings also support configuring DNS over HTTPS (DoH) where the selected resolver and Windows configuration support it. (support.microsoft.com)
Do not simply copy numbers from a random forum.
Know which resolver you are choosing and why.
Common Public DNS Services
Well-known public resolvers include services operated by companies such as:
Cloudflare
Quad9
They can provide alternatives to ISP resolvers.
But “public DNS” does not automatically mean:
faster
more private
more secure
more suitable for business
Those properties depend on:
provider
location
policy
filtering
logging
encryption
network design
Choose deliberately.
What Is DNS over HTTPS?
Traditional DNS queries can often be visible to networks between you and the resolver.
DNS over HTTPS encrypts DNS queries within HTTPS traffic.
Microsoft supports DoH configuration in current Windows networking, and Windows Server 2025 DNS Server gained generally available DoH support in June 2026. (support.microsoft.com) (support.microsoft.com)
DoH can improve privacy and resistance to DNS manipulation.
But encrypted DNS still does not make a malicious website safe.
It protects the lookup transport, not the destination itself.
Business Networks Need More Caution
This is where generic consumer advice becomes risky.
A business may intentionally use DNS for:
Active Directory
internal servers
web filtering
security controls
branch connectivity
VPN
split DNS
Changing a laptop from:
company DNS
to:
8.8.8.8
may cause public websites to work while breaking access to:
file servers
internal applications
printers
domain services
That is not a successful fix.
It is simply bypassing the organisation’s DNS architecture.
Active Directory Depends Heavily on DNS
Windows domain environments use DNS to locate services such as domain controllers.
If a domain-joined PC points directly to a random public resolver rather than the organisation’s internal DNS infrastructure, domain functionality can behave incorrectly.
This can affect:
sign-in
Group Policy
file shares
service discovery
On domain-joined machines:
do not replace corporate DNS with public DNS as a casual troubleshooting step.
Let the internal DNS server resolve internal names and forward external requests appropriately.
VPNs and Split DNS
A VPN may intentionally use different DNS servers while connected.
This allows:
internal.company
to resolve through corporate DNS while ordinary internet names behave differently.
Changing the Windows DNS configuration manually can break that design.
If:
everything works without VPN
but:
internal names fail with VPN
investigate:
VPN DNS configuration
split DNS
route/policy
rather than hard-coding a public resolver.
Protective DNS Can Be a Security Control
For businesses, DNS can do more than translate names.
Protective DNS services can block known malicious destinations before a connection is established.
The NCSC describes Protective DNS as a recursive DNS service that blocks access to domains known to be malicious. (ncsc.gov.uk)
Private-sector organisations that do not qualify for NCSC PDNS can consider appropriate commercial protective DNS services. (ncsc.gov.uk)
That means replacing business DNS with a generic public resolver could remove:
malware blocking
phishing protection
policy enforcement
Be careful what you are bypassing.
Changing DNS Can Hide the Real Fault
Suppose:
ISP DNS intermittently fails.
You change the laptop to another resolver.
Everything works.
That's useful evidence.
But now ask:
Why was the normal DNS service failing?
If every device using the router has the same problem, investigate:
ISP DNS
router DNS forwarding
DHCP configuration
rather than permanently hand-configuring every workstation.
Fixing the root cause is cleaner.
What If Every Device Suddenly Goes to the Wrong Websites?
This is more serious.
If:
PC
phone
laptop
all begin resolving websites incorrectly, investigate:
router DNS
DHCP
upstream resolver
security compromise
The NCSC published an advisory in 2026 describing attackers exploiting routers to alter DHCP/DNS settings for DNS hijacking activity. (ncsc.gov.uk)
So unexplained DNS changes across multiple devices should not be dismissed as a browser issue.
Check the network infrastructure.
Router vs PC DNS
Your PC may receive DNS automatically from DHCP.
Commonly that means:
PC → router DNS proxy/forwarder → ISP/public DNS
or:
PC → corporate DNS server → external forwarder
That means changing DNS directly on the PC bypasses part of the normal chain.
This can be useful diagnostically.
But it does not automatically tell you which component in the original chain failed.
The Better Diagnostic Sequence
If websites are not resolving:
1. Confirm general network connectivity.
2. Check whether the problem affects one device or many.
3. Run nslookup.
4. Identify the DNS server currently being used.
5. Run:
ipconfig /flushdns
6. Retry the lookup.
7. Test another trusted resolver temporarily if appropriate.
8. If the alternative works, investigate the original DNS path.
9. On business PCs, check whether internal DNS, filtering or VPN requirements exist before making permanent changes.
10. If every device is affected, investigate the router/DHCP/upstream network.
The key principle is:
Use a DNS change as a diagnostic test first, not as a magic internet fix.
Does DNS Make the Internet Faster?
Sometimes it can make browsing feel slightly faster because name resolution completes more quickly.
It does not increase the raw capacity of your broadband connection.
Imagine:
ISP DNS lookup = 150 ms
alternative DNS = 20 ms
The website may begin loading sooner.
But once the download begins, your:
80 Mbps
500 Mbps
1 Gbps
connection remains whatever it was before.
That distinction should be clear.
Don't Change DNS to Fix Everything
I would not use DNS changes as a first response to:
Wi-Fi dropping
slow Ethernet
100 Mbps negotiation
packet loss
video-call jitter
VPN disconnects
printer problems
high latency
Those symptoms point elsewhere.
Troubleshoot the failing layer.
How Hamilton Group Can Help
DNS problems can look like general internet problems because applications rely on name resolution constantly.
Hamilton Group can help diagnose:
Windows DNS issues
business DNS
Active Directory DNS
Microsoft 365 connectivity
DNS forwarding
DHCP
protective DNS
VPN split DNS
DNS over HTTPS
router and network problems
For businesses, we can determine whether changing DNS is genuinely fixing a resolver problem or simply bypassing an internal security or network configuration that needs proper attention.
Visit hgmssp.com or call 0330 043 0069 to discuss business networking and IT support.