FREQUENTLY ASKED QUESTIONS

DNS (Domain Name System) translates human-readable domain names like example.com into IP addresses that computers use to communicate. When you visit a website, your device queries a DNS resolver, which recursively searches authoritative DNS servers to find the correct IP address. This hierarchical distributed database system enables the internet to function by mapping names to network addresses across billions of devices globally.

The most common DNS record types include A records (IPv4 addresses), AAAA records (IPv6 addresses), CNAME records (domain aliases), MX records (mail servers), TXT records (text data including SPF and DKIM), NS records (nameservers), and SOA records (zone authority information). Each record type serves a specific purpose in DNS infrastructure, from routing web traffic to email delivery and domain ownership verification.

A DNS resolver is a server that handles DNS queries on behalf of client devices, translating domain names into IP addresses. The resolver you use affects your browsing speed, privacy, and security, as it can see all domains you visit. Public DNS resolvers like Cloudflare 1.1.1.1, Google 8.8.8.8, and Quad9 9.9.9.9 offer varying levels of performance, filtering, and privacy protection compared to ISP-provided resolvers.

You can find DNS records using command-line tools like dig or nslookup, or by using online DNS lookup tools like dnsrecon.io. Enter the domain name and specify the record type (A, AAAA, MX, TXT, etc.) to retrieve the authoritative DNS data. DNS lookup tools query authoritative nameservers directly to provide accurate, real-time information about a domain's DNS configuration.

Authoritative DNS servers store the actual DNS records for domains and provide definitive answers to queries about those domains. Recursive DNS servers (resolvers) act as intermediaries that query authoritative servers on behalf of clients, caching results to improve performance. Authoritative servers are configured by domain owners, while recursive servers are operated by ISPs, organizations, or public DNS providers.

DNS propagation is the time it takes for DNS changes to spread across all DNS servers worldwide after updating your records. Propagation typically takes 5 minutes to 48 hours depending on TTL (Time To Live) values, caching by resolvers, and network conditions. Lower TTL values result in faster propagation but higher query loads on authoritative servers.

DNS changes may not appear immediately due to caching at various levels, including your local device, router, ISP resolver, and public DNS servers. Each DNS record has a TTL that determines how long servers cache the data before requesting fresh information. Clearing local DNS cache, flushing resolver caches, or waiting for the TTL to expire will allow new records to propagate.

DNS propagation checking tools query DNS servers from multiple geographic locations worldwide to verify if your DNS changes have propagated. These tools show real-time results from different countries and DNS providers, helping you identify which regions or resolvers still have old cached data. Global propagation checking is essential when migrating websites, changing nameservers, or updating critical DNS records.

Yes, TTL (Time To Live) directly controls DNS propagation speed by specifying how long resolvers can cache a DNS record before re-querying authoritative servers. Lower TTL values (300-600 seconds) enable faster propagation but increase DNS query volume, while higher TTL values (3600-86400 seconds) reduce server load but slow propagation. It is best practice to lower TTL values 24-48 hours before making DNS changes, then raise them afterward.

SPF (Sender Policy Framework) is a DNS TXT record that lists authorized mail servers for your domain, preventing email spoofing and phishing. When receiving mail servers check SPF records, they verify that incoming emails originate from approved sources, reducing spam and improving email deliverability. Properly configured SPF records are essential for domain reputation and email security.

DKIM (DomainKeys Identified Mail) adds cryptographic signatures to outgoing emails using a private key, with the public key published in DNS TXT records. Receiving servers verify these signatures against the DNS-published public key to confirm emails have not been tampered with and originate from the claimed domain. DKIM authentication protects against email spoofing, improves sender reputation, and increases deliverability rates.

DMARC (Domain-based Message Authentication, Reporting and Conformance) is a DNS policy that tells receiving servers what to do when SPF or DKIM checks fail, with options to quarantine or reject suspicious emails. DMARC builds on SPF and DKIM by adding alignment checks and providing aggregate reports about email authentication failures. Implementing DMARC protects your domain from being used in phishing attacks and provides visibility into email delivery issues.

SPF record validation tools parse your DNS TXT records to check syntax, lookup limits, and authorization mechanisms for errors. Valid SPF records must contain fewer than 10 DNS lookups, use proper syntax, and include all legitimate mail servers. SPF validators identify issues like too many lookups, invalid mechanisms, and missing authorization that can cause email delivery failures.

Emails may go to spam due to missing or misconfigured email authentication (SPF, DKIM, DMARC), poor sender reputation, blacklisted IP addresses, or spam-like content. Verify your DNS records include proper SPF, DKIM, and DMARC configuration, check if your sending IP is on any DNS blacklists, and ensure your email content and headers follow best practices. Warming up new sending IPs gradually and maintaining low complaint rates improves deliverability.

DNSSEC (DNS Security Extensions) adds cryptographic signatures to DNS records, preventing DNS spoofing and cache poisoning attacks by allowing resolvers to verify data authenticity. DNSSEC creates a chain of trust from root DNS servers to your domain, ensuring DNS responses have not been tampered with. Enabling DNSSEC protects users from being redirected to malicious sites and is increasingly required for high-security domains. Use the DNSSEC Validator to check your domain.

DNSSEC validation tools check the complete chain of trust from root servers through TLDs to your domain's signed records, verifying DNSKEY, RRSIG, DS, and NSEC/NSEC3 records. Proper DNSSEC implementation requires signed zone files at your authoritative nameservers and DS records published at your domain registrar. DNSSEC validators identify broken chains of trust, expired signatures, and configuration errors that prevent secure DNS resolution. Try the DNSSEC Validator to check your domain's chain of trust.

Reverse DNS (PTR records) maps IP addresses back to domain names, enabling verification that an IP address is associated with a legitimate domain. Email servers often check PTR records to validate sending servers, and missing or mismatched reverse DNS can cause email rejection or spam filtering. Proper PTR record configuration is essential for mail servers, and many networks require reverse DNS for security and troubleshooting purposes.

DNS blacklist checking tools query multiple RBL (Real-time Blackhole List) databases to determine if your IP address is listed for spam, abuse, or malicious activity. Major blacklists include Spamhaus, Barracuda, and SORBS, each with different listing criteria and removal procedures. Regular blacklist monitoring is critical for maintaining email deliverability and identifying compromised systems.

Blacklist removal requires identifying the listing reason, fixing the underlying issue (compromised systems, open relays, spam complaints), and submitting a delisting request to each RBL operator. Some blacklists automatically remove IPs after a period of good behavior, while others require manual review and proof of remediation. Preventing future listings requires proper email authentication, security hardening, and monitoring outbound traffic for abuse.

DNS speed testing tools measure query response times from multiple public DNS resolvers to your location, testing both cached and uncached lookups. Popular DNS resolvers like Cloudflare 1.1.1.1, Google 8.8.8.8, Quad9 9.9.9.9, and OpenDNS 208.67.222.222 have different performance characteristics depending on geographic location and network topology. Choosing the fastest resolver for your location can significantly improve web browsing performance and reduce page load times.