Question 1

What's the difference between A and AAAA?

Accepted Answer

A records hold IPv4 addresses (like 192.0.2.42, ~4 billion possible). AAAA records hold IPv6 addresses (like 2001:db8::1, ~340 undecillion possible). IPv6 adoption is around 45% of global traffic as of 2026; major sites publish both. Missing AAAA isn't broken — clients fall back to IPv4 — but it does mean slower mobile performance on IPv6-only carriers (Verizon, T-Mobile, EE in some regions). The tool checks both and flags AAAA absence as a recommendation, not a failure.

Question 2

What is reverse DNS / PTR?

Accepted Answer

Reverse DNS (the PTR record) maps an IP address back to a hostname — the inverse of A/AAAA. PTR records live in the in-addr.arpa zone (for IPv4) or ip6.arpa (for IPv6). They're set by whoever controls the IP — usually your hosting provider. Common patterns: ec2-198-51-100-42.compute.amazonaws.com (AWS), 1-2-3-4.region.compute.googleusercontent.com (GCP), gateway.azure.com (Azure). The PTR string is your fastest signal of where the site is hosted.

Question 3

What's PTR/A reciprocity?

Accepted Answer

Forward (A) and reverse (PTR) DNS should agree: example.com → 192.0.2.42 → mail.example.com (NOT example.com). Reciprocity means PTR points back to a hostname that also has an A record pointing to the same IP. Mail servers reject email from IPs without proper PTR/A reciprocity since it indicates a misconfigured or potentially-spoofed sender. The tool shows the chain so you can spot mismatches — common when DNS migrates between providers and the reverse zone doesn't get updated.

Question 4

How do I read the PTR hostname?

Accepted Answer

AWS: ec2-{IP-with-dashes}.{region}.compute.amazonaws.com or .compute-1.amazonaws.com (us-east-1 only). GCP: {dashes-IP}.bc.googleusercontent.com or {something}.googleusercontent.com. Azure: arr-{datacenter}-{node}.azurewebsites.net or similar. Cloudflare: not a hosting CDN — Cloudflare PTRs return 'one.one.one.one' (the 1.1.1.1 brand). Vercel: doesn't set custom PTRs, so PTR returns Vercel's underlying provider (usually AWS us-east-1).

Question 5

Can I look up by IP directly?

Accepted Answer

Yes — paste an IPv4 or IPv6 in the hostname field. The tool detects the format and switches to reverse-only mode (PTR lookup with no forward A query). Useful when you have an IP from a server log or email header and want to know where it's hosted. The tool doesn't perform geolocation here (paid APIs); pair this with the IP Geolocation tool for that.

Question 6

Does this tool log my queries?

Accepted Answer

Digital Heroes doesn't log. Cloudflare DoH logs anonymized queries per their resolver privacy policy.

IP lookup. A record plus reverse.

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