DMARC Lookup Jul 3, 2026

Why DMARC Forensic Reports Are Almost Never Deployed — ruf=, Privacy, and the pct= Gradual Rollout Strategy

DMARC forensic reports (ruf=) send full copies of failing messages to a specified inbox — which means receiving copies of phishing emails, confidential business email, and PII. Here's why ruf= is almost never deployed (Google and Microsoft don't send them, privacy obligations, volume), how the pct= percentage tag enables gradual p=reject rollout, and why external third-party DMARC reporting services need DNS verification before they can receive your reports.

DNS Lookup Jul 3, 2026

DNSSEC Protects Against Cache Poisoning — Not the Attacks That Actually Cause DNS Outages

DNSSEC signs DNS records cryptographically — protecting against cache poisoning (Kaminsky's 2008 attack) but doing nothing about registrar account compromise, BGP hijacking, or misconfigured records. Here's how DNSSEC's chain of trust works (root → TLD → domain), why expired RRSIG signatures cause SERVFAIL for DNSSEC-validating resolvers including Google and Cloudflare, and why only ~3-5% of .com domains have DNSSEC despite most TLDs being signed.

WHOIS Lookup Jun 29, 2026

Why Major Organizations Accidentally Let Their Domains Expire — and the Monitoring That Prevents It

Domain expiry is predictable months in advance — yet Microsoft Hotmail UK, Foursquare, and dozens of others have accidentally let critical domains expire. Here's the four root causes of accidental expiry (expired payment method, abandoned monitoring email, administrative responsibility gap, forgotten legacy domain), the redemption timeline that provides recovery opportunity, and why renewal notifications should never go to the email domain that's expiring.

BIMI Lookup Jun 29, 2026

A BIMI Logo Doesn't Stop Phishing — What BIMI's Security Model Actually Protects Against

BIMI's logo signals trademark ownership and DMARC enforcement — not email quality or sender reputation. It protects against spoofing the exact registered domain, not against lookalike domains (examp1e.com). Here's BIMI's four-layer authentication stack context, what VMC vs CMC actually certifies (trademark ownership, not email quality), why DMARC p=reject is the real security benefit in the BIMI requirement chain, and why major brands remain the primary BIMI adopters.

SSL Checker Jun 26, 2026

Your SSL Certificate Was Valid Yesterday — Here's How It Can Fail Today Without You Changing Anything

A certificate can fail after issuance without any change on your part — revocation invalidates correctly-issued certificates when private keys are compromised, CT log disqualification can affect certificates whose SCTs came from that log, and intermediate CA incidents can distrust entire chains. Here's how certificate revocation works (CRL vs OCSP vs OCSP Stapling), the soft-fail problem that makes revocation unreliable, and the five-component monitoring stack for active certificate health.

SPF Lookup Jun 25, 2026

SPF Records Go Stale Without You Touching Them — The Flattening Trap and How to Monitor Instead

SPF flattening solves the 10-lookup PermError by replacing include: mechanisms with their resolved IP addresses — but silently breaks every time a provider updates their IP ranges, which happens regularly without notification. Here's why SPF records go stale without anyone touching them, the specific maintenance trap of flattened records, why the ptr: mechanism should never be used, and how DMARC aggregate reports provide the best automated SPF monitoring.

Reverse DNS Jun 25, 2026

How to Read a PTR Record Like a Network Investigator — Email Forensics, ISP Naming Patterns, and FCrDNS

A PTR record can say anything — anyone who controls a server can configure their reverse DNS to claim any hostname. FCrDNS (Forward-Confirmed Reverse DNS) verifies authenticity by checking that the PTR hostname resolves back to the original IP. Here's how to read ISP and datacenter naming conventions in PTR records, how reverse DNS reveals email header forgery, and why PTR record changes can indicate BGP hijacking.

Blacklist Checker Jun 23, 2026

Your IP Is on a Blacklist — Here's What the Specific List Tells You About Why and What to Do Next

Spamhaus ZEN checks four separate lists simultaneously — SBL (observed spam operations), XBL (compromised machines), PBL (residential/dynamic IPs that should use relays), and DBL (spam domains) — and being on each requires completely different remediation. Here's the triage guide for each list type, why PBL is the most misunderstood listing (it means "wrong IP type for direct delivery," not "you sent spam"), and reputation repair timelines after delisting.

Ping Tool Jun 23, 2026

A Successful Ping Doesn't Mean Your Service Is Running — What ICMP Actually Tells You and What It Doesn't

A successful ping proves the host's IP is reachable — not that any service is running. A failed ping could mean the host is down, ICMP is firewalled, or there's packet loss somewhere in the path — three completely different problems with different solutions. Here's what ping can and cannot diagnose, how to interpret latency patterns (consistent, variable/jitter, increasing), and the correct escalation from ping to traceroute to port check to service-level testing.

Port Scanner Jun 23, 2026

Shodan Already Has Your Open Ports — What Attackers Learn From Port Scans and Why You Should Run Them Too

The entire internet-facing IPv4 space can be scanned in under an hour — Shodan and Censys already have your server's open ports catalogued. Here's what banner grabbing reveals (exact software versions → known CVEs), the difference between open/closed/filtered port states and why "filtered" is the preferred security posture, why SYN scanning doesn't appear in application logs, and what to look for when port scanning your own infrastructure.

NS Lookup Jun 23, 2026

Changing Nameservers Transfers Authority for Your Entire Domain — Here's Why That Makes NS Hijacking Uniquely Dangerous

Changing nameservers transfers authority for your entire domain — website, email, subdomains, authentication records — to whoever controls the new nameservers. Here's how nameserver hijacking works (registrar account compromise, social engineering of registrar support), what registry locks actually protect against, the glue record attack surface that bypasses NS monitoring, and why proactive NS record monitoring is the minimum security practice for business-critical domains.

MX Lookup Jun 23, 2026

MX Records Are Public Reconnaissance Data — Here's What Attackers Learn and How to Defend Against It

MX records are public reconnaissance data — attackers use them to identify email providers, target backup MX servers that have weaker filtering than primary MX, and exploit dangling MX records pointing to decommissioned servers. Here's the backup MX vulnerability, how null MX (RFC 7505) protects parked domains, the TTL preparation step for email migrations, and why using "mx" in SPF creates maintenance traps.