Troubleshooting Guides

Step-by-step guides to diagnose and fix common technical problems.

Browse by Category

DNS Issues12 guides
Email Deliverability14 guides
Security & SSL9 guides
Network & Connectivity6 guides
Web & Performance7 guides

All Troubleshooting Guides

DNS Propagation DelayLearn why DNS changes take time to propagate, how to diagnose propagation issues, and how to speed up DNS updates using WarpCheck diagnostic tools.
DNS Record MisconfigurationDiagnose and fix common DNS record misconfigurations including wrong A records, missing MX records, and conflicting CNAME entries.
Nameserver Not RespondingTroubleshoot nameserver failures causing DNS resolution issues. Diagnose unresponsive nameservers and fix domain resolution problems.
DNSSEC Validation FailureDiagnose and resolve DNSSEC validation failures including expired signatures, missing DS records, and algorithm mismatches.
DNS TTL Too HighLearn why excessively high DNS TTL values cause slow propagation and how to choose the right TTL for your domain.
DNS Cache PoisoningUnderstand DNS cache poisoning attacks, detect compromised DNS responses, and protect your domain with DNSSEC and secure configurations.
DNS Record Not FoundDiagnose NXDOMAIN errors and missing DNS records. Learn why DNS lookups return "record not found" and how to resolve them.
DNS Zone Transfer ExposedDetect and fix exposed DNS zone transfers that leak your entire domain structure. Secure AXFR configuration on nameservers.
DNS Delegation BrokenDiagnose and repair broken DNS delegation causing domain resolution failures. Fix lame delegation and nameserver mismatches.
DNS Glue Records MissingDiagnose and fix missing glue records that cause circular DNS resolution failures for domains using in-domain nameservers.
DNS Recursion DisabledUnderstand when DNS recursion should be enabled or disabled and how to troubleshoot resolution failures caused by recursion settings.
DNS Amplification RiskIdentify DNS amplification vulnerabilities on your nameservers and learn how to prevent your infrastructure from being used in DDoS attacks.
Invalid SPF RecordLearn why SPF records become invalid and how to diagnose and fix SPF configuration issues using WarpCheck's DNS analysis tools.
DKIM Signature InvalidDiagnose and fix DKIM signature validation failures. Learn common causes and how to verify DKIM configuration.
DMARC Policy FailureUnderstand why DMARC policy failures occur and how to fix alignment issues between SPF, DKIM, and your sending domain.
Email Going to SpamDiagnose why emails are landing in spam folders. Check SPF, DKIM, DMARC, blacklist status, and sending reputation.
SMTP Authentication FailedDiagnose SMTP authentication errors (535 5.7.8). Fix login failures, app passwords, and relay access denied issues.
SPF PermErrorDiagnose and fix SPF permanent errors (PermError) caused by syntax issues, too many lookups, or invalid mechanisms.
SPF Too Many LookupsFix SPF records exceeding the 10 DNS lookup limit. Learn to flatten SPF records and optimize mechanisms for email deliverability.
DMARC Quarantine TriggeredUnderstand why DMARC quarantine is triggered and how to fix alignment issues to prevent legitimate emails from being quarantined.
Mail Server BlacklistedCheck if your mail server is blacklisted and learn how to get delisted. Diagnose domain and IP blacklist issues affecting email delivery.
Reverse DNS MissingDiagnose and fix missing reverse DNS (PTR) records that cause email delivery failures and blacklisting.
HELO Hostname MismatchDiagnose and fix SMTP HELO/EHLO hostname mismatches that cause email delivery issues and spam classification.
DKIM Body Hash MismatchDiagnose and fix DKIM body hash mismatch errors where the bh= tag doesn't match the actual email body content.
SMTP TimeoutDiagnose and fix SMTP connection timeouts caused by network issues, firewall blocks, or server overload.
Email Delivery DelayedDiagnose why emails are delayed. Check greylisting, server queues, DNS issues, and throttling that cause slow email delivery.
IP BlacklistedCheck if your IP is blacklisted and learn how to get delisted. Diagnose IP reputation problems using WarpCheck.
High Packet LossIdentify the cause of high packet loss affecting your network. Use ping, traceroute, and latency tools to pinpoint the problem hop.
Network Latency SpikesDiagnose and fix intermittent network latency spikes causing slow connections. Identify congested hops and routing issues.
Port Blocked by FirewallCheck if network ports are blocked by firewalls. Diagnose connectivity issues for web, email, and application services.
ASN Routing IssuesIdentify BGP routing issues, ASN misconfigurations, and route leaks affecting network connectivity and performance.
ISP Peering ProblemIdentify ISP peering and transit issues causing connectivity problems. Diagnose network path issues between providers.
SSL Certificate ExpiredDiagnose and resolve SSL certificate expiration issues. Check certificate validity, renewal status, and HTTPS configuration.
SSL Certificate Chain IncompleteFix incomplete SSL certificate chains that cause trust errors in browsers. Diagnose missing intermediate certificates.
TLS Handshake FailureDiagnose and fix TLS handshake failures caused by protocol mismatches, cipher suite incompatibilities, and certificate errors.
Weak Cipher SuitesIdentify and disable weak cipher suites on your server. Improve SSL/TLS security by enabling modern, strong encryption algorithms.
HSTS Not EnabledLearn why HSTS is important, how to enable it, and how to fix common HSTS configuration mistakes for better HTTPS security.
Certificate Hostname MismatchFix SSL certificate hostname mismatch errors (ERR_CERT_COMMON_NAME_INVALID). Diagnose CN and SAN configuration issues.
Self-Signed CertificateUnderstand why self-signed certificates cause trust errors and how to replace them with trusted CA-issued certificates.
TLS Version DeprecatedUpgrade from deprecated TLS 1.0 and TLS 1.1 to modern TLS 1.2/1.3. Fix compliance and security issues with TLS version configuration.
Insecure RedirectDetect and fix insecure redirects that expose users to man-in-the-middle attacks. Ensure proper HTTPS redirect chains.
Mixed Content WarningsResolve mixed content warnings caused by loading HTTP resources on HTTPS pages. Diagnose and fix insecure resource loading.
Website Slow LoadingDiagnose slow website performance. Measure TTFB, load time, CDN latency, and server response to identify bottlenecks.
HTTP Redirect LoopDiagnose and fix redirect loops causing ERR_TOO_MANY_REDIRECTS. Identify misconfigured redirects between HTTP/HTTPS and www/non-www.
500 Internal Server ErrorDiagnose and fix HTTP 500 internal server errors. Identify server-side issues causing your website to return error pages.
Robots.txt Blocking PagesDiagnose robots.txt misconfigurations that block search engines from indexing your important pages. Fix crawl issues.
Canonical Tag MisconfigurationDiagnose and fix canonical tag errors causing duplicate content and SEO problems. Verify rel=canonical implementation.
Gzip Compression DisabledCheck if gzip/brotli compression is enabled and learn how to configure server-side compression for better performance.