DNS Lookup

DoH wraps DNS queries in standard HTTPS requests, so they look like normal web traffic to anyone watching. Cloudflare 1.1.1.1, Google 8.8.8.8, and Quad9 9.9.9.9 all offer DoH endpoints. The benefit: your ISP can't easily see or modify your DNS lookups (which they often do for ad insertion, parental-control filtering, or surveillance). The trade-off: your DNS provider sees them instead, so pick one you trust.

Several reasons. (1) GeoDNS — large services (Google, Netflix, Cloudflare) deliberately return different IPs from different regions to route traffic to nearby servers. (2) DNS-based load balancing — round-robin or weighted distribution across multiple addresses. (3) Stale propagation — recently changed records still cached at some resolvers. (4) DNS hijacking — a hostile network or compromised resolver returning fake answers. Multi-probe makes all of these visible at once.

A records map a domain name to an IPv4 address (32-bit, like 93.184.216.34). AAAA records map to an IPv6 address (128-bit, like 2606:2800:220:1:248:1893:25c8:1946). A domain can have one or both; modern services typically run dual-stack with both record types. Browsers prefer IPv6 when available.

Nothing on its own — TXT is a free-form string. Real applications: SPF and DMARC for email authentication, DKIM keys for email signing, domain ownership verification (Google, Microsoft, ACME challenges), and a long tail of vendor-specific configuration. Inspecting TXT records is often the first step when debugging email deliverability or domain-ownership issues.

Mail servers try lower-priority numbers first. A typical setup has a primary at priority 10 and a backup at priority 20; if 10 is down, mail flows to 20. Some setups use round-robin within a single priority for load distribution. The lookup returns priority and hostname for each MX target.

Up to the record's TTL value. A record with TTL=300 (5 minutes) propagates in 5 minutes from when the change is published. TTL=86400 (24 hours) takes a day. Some legacy DNS resolvers ignore TTLs and cache for fixed periods, so 'full' propagation can take 24–48 hours regardless. Multi-probe is the best way to monitor this in real time.