12 Critical DNS Errors That Can Break Your Website (+ Quick Fixes)

DNS errors can take your web site offline in seconds. The stats are alarming: 72% of organizations confronted a DNS assault in 2024, and practically half concerned DNS hijacking. Attackers manipulate DNS queries to redirect customers to malicious servers, creating main vulnerabilities.

When DNS features accurately, every little thing from e mail supply to internet shopping works easily. However DNS issues can set off downtime, gradual efficiency, failed connections, and even knowledge breaches. These points are sometimes brought on by easy misconfigurations — giving attackers precisely what they need.

On this information, we’ll stroll by 12 of probably the most frequent DNS points, clarify what causes DNS errors, and share recommendations on the best way to repair DNS errors rapidly. Whether or not you’re coping with cryptic messages or unexplained outages, this DNS troubleshooting reference will assist preserve your web site operating easily.

This error means a DNS lookup failed fully — the system couldn’t discover any IP tackle for the requested area.

The “NXDOMAIN” label stands for “Non-Existent Area.” That might imply:

• A typo within the area identify
• An unregistered or expired area
• Corrupted native DNS cache
• Unsuitable DNS server settings
• Conflicting VPN, antivirus, or firewall guidelines
• A misconfigured hosts file
• Chrome-specific flags interfering with DNS

This leads to full inaccessibility. Chrome exhibits “This web site can’t be reached,” whereas Firefox shows “We’re having bother discovering that web site.”

• Double-check the area identify
• Flush DNS cache (ipconfig /flushdns on Home windows, Terminal instructions for macOS)
• Renew your IP tackle
• Swap to public DNS (e.g., 8.8.8.8 or 1.1.1.1)
• Examine your hosts file
• Briefly disable VPN/firewall
• Affirm that A information are current and level to a legitimate server

In contrast to NXDOMAIN, SERVFAIL happens when the DNS server can’t full a legitimate lookup — although the area exists.

• DNSSEC validation failures (expired or mismatched keys)
• Zone file misconfigurations
• Lacking glue information
• Overloaded or offline authoritative identify servers
• Extreme CNAME chains (recursive depth exceeded)
• Firewall or routing points

Customers and bots can’t entry your web site or ship e mail. SERVFAIL additionally harms web optimization since serps can’t crawl your area constantly.

• Validate DNSSEC signatures
• Assessment and proper zone file syntax
• Examine glue information and identify server delegation
• Monitor server masses and guarantee redundancy
• Maintain CNAME chains beneath eight entries

A REFUSED error means the DNS server intentionally rejected your question.

• Entry restrictions or safety insurance policies
• IP filtering or country-based blocks
• Unauthorized requests (e.g., zone transfers)
• Protocol mismatches (e.g., blocked TCP connections)
• Firewall guidelines or DNS server misconfigurations

These dns issues trigger web site inaccessibility and repair interruptions. Customers would possibly see “ERR_CONNECTION_REFUSED,” and apps counting on DNS cease functioning.

• Flush your native DNS
• Swap to automated or public DNS settings
• Take a look at with Google (8.8.8.8) or Cloudflare (1.1.1.1)
• Examine firewall and port guidelines (UDP/TCP on port 53)
• Confirm that your registrar and internet hosting supplier have matching identify servers

This occurs when the DNS question occasions out earlier than getting a response — usually with no seen error code.

• Sluggish or overloaded DNS servers
• Dangerous routing paths or excessive latency
• DNS servers situated too far geographically
• Blocked or filtered DNS site visitors in your community
• Useful resource-starved DNS resolvers

DNS timeouts usually go unnoticed in logs however trigger vital slowdowns. Google stories that bounce charges enhance dramatically when web page load occasions exceed 3–5 seconds.

• Use a number of DNS servers for failover
• Select optimized, low-latency DNS providers
• Monitor DNS response time utilizing instruments like DNSPerf
• Scale back TTLs to reduce wait occasions
• Think about using a CDN for geo-distributed decision

In case your MX information are misconfigured, your group’s e mail can cease working fully.

• MX information pointing to CNAMEs (which is invalid)
• Syntax errors or lacking dots in hostnames
• Duplicate information or incorrect precedence values
• Data pointing to decommissioned servers
• Failure to confirm area possession

E mail bouncebacks, spam flags, and supply failures — particularly with suppliers like Gmail or Outlook that depend on strict DNS validation.

• Level MX information to A information (not CNAMEs)
• Use precedence values correctly (lowest = major server)
• Affirm possession through DNS TXT information
• Clear up outdated or duplicate entries
• Take a look at configurations with MXToolbox

Reverse lookups (rDNS) map IPs again to domains. They’re important for e mail belief and authentication.

• Lacking PTR information
• Mismatched ahead (A) and reverse (PTR) information
• Dynamic IPs with out PTR setup
• Internet hosting suppliers who don’t help customized rDNS
• Blacklisted IPs

• Ask your ISP or host to assign a legitimate PTR
• Use static IPs for outbound e mail
• Match A and PTR entries precisely
• Arrange SPF, DKIM, and DMARC for added belief

DNS adjustments don’t apply immediately — they take time to propagate worldwide.

• Excessive TTL (Time-to-Reside) values
• ISP-level caching past your management
• Delays in world DNS root servers
• Gradual regional infrastructure

Customers may even see outdated content material or get bounced emails. It could actually additionally confuse serps throughout web site migrations.

• Decrease TTL to 300–600 seconds earlier than deliberate adjustments
• Monitor progress utilizing DNSChecker or WhatsMyDNS
• Clear native and browser DNS caches
• Take into account CDN providers to speed up decision

This broad class consists of all of the little errors that quietly break DNS behind the scenes.

• Typos in IP addresses
• A number of CNAMEs assigned to 1 identify
• Ahead and reverse mismatches
• Data nonetheless pointing to legacy infrastructure

These silent dns issues can result in man-in-the-middle assaults, downtime, or redirect errors.

• Audit your DNS repeatedly
• Use a DNS supplier that tracks adjustments and historical past
• Use dig or nslookup to validate information manually
• Implement DNS failover for key providers

TTL settings management how lengthy information are cached by resolvers. Longer values scale back load however decelerate updates.

• Leaving default TTL at 86,400 seconds (24 hours)
• Not reducing TTL earlier than main adjustments
• Making an attempt to chop down on question quantity

Excessive TTL means quick efficiency and low question value — however DNS adjustments can take days to propagate.

Use 1800–3600s TTL for dynamic information, and decrease it to 300s earlier than migrations.

Open resolvers reply to queries from anybody. That makes them susceptible to DNS amplification and spoofing assaults.

• Misconfigured routers or firewalls
• DNS servers permitting unrestricted recursion
• No ACLs (Entry Management Lists) in place

You can unknowingly take part in DDoS assaults or expose your infrastructure to poisoning.

• Disable recursion on public-facing servers
• Apply IP-based restrictions
• Use response fee limiting (RRL)
• Comply with BCP 38 to stop spoofed site visitors

Outdated DNS information pointing to inactive servers or providers can quietly trigger decision failures or safety dangers.

• Poor DNS hygiene
• No cleanup after server decommissioning
• Lack of change administration throughout infrastructure updates

Stale information will be exploited in subdomain takeovers or end in site visitors being routed to unintended locations.

• Scheduled DNS audits
• DNS scavenging instruments
• Handbook assessment of crucial entries
• Decommissioning workflows tied to DNS updates

Your authoritative identify servers are the ultimate supply of fact. In the event that they’re left open, you threat complete area compromise.

• Permitting recursion on authoritative servers
• No firewall or ACLs on zone transfers
• No DNSSEC signing

From cache poisoning to DDoS, unsecured identify servers open the door to widespread abuse.

• Turning off recursion
• Proscribing zone transfers with TSIG
• Utilizing DNSSEC to confirm knowledge integrity
• Inserting primaries behind firewalls or as hidden masters

DNS errors can really feel like a black field — till they take your web site offline or break your e mail system. However most DNS errors are preventable with the fitting setup and common upkeep.

By understanding what causes DNS errors, performing constant dns troubleshooting, and understanding the best way to repair DNS errors once they seem, you achieve management over one of the crucial crucial layers of your digital infrastructure.

From gradual lookups to hijacked information, these frequent DNS points don’t need to catch you off guard. Bookmark this information, audit your information, and keep forward of DNS issues earlier than they affect your enterprise.