A broken IPv6 path does not take a dual-stack site down. It adds real, measurable delay for a share of visitors while an IPv4-only uptime check keeps reporting "up" the entire time.
A real CNAME can never sit at a zone apex, so every provider invented its own workaround: ALIAS, ANAME, CNAME flattening. Three names for roughly the same trick, with real differences in TTL handling and DNSSEC behavior, plus a newer standards-based alternative most guides skip.
DNSSEC fails closed: a broken chain of trust returns SERVFAIL, not a wrong answer. Two real incidents, Slack in 2021 and a TLD-wide DENIC outage in 2026, show the two root causes that actually happen, and the fast path to telling them apart.
Every subdomain takeover guide is written for a security team hunting exposure. Most takeovers start as an ops mistake: a CNAME left behind after a vendor migration or a decommissioned SaaS tool, with nobody deleting the record.
DNS propagation isn't a transport mechanism, it's cache expiry. Negative caching, not TTL alone, explains why a fresh record can lag. Here's how to actually verify a change, and why that verification never really stops.
DNS-AID proposes publishing AI agents through DNS records instead of well-known URIs. Here is what the draft actually specifies, what the Linux Foundation launch means, and why the record shape is still inconsistent across every implementation we checked.
Domain monitoring and DNS monitoring watch two different layers of the same name: registration versus resolution. Here is what each one catches, where they overlap at the nameserver, and which layer catches which outage, so you know why you need both.
Detecting DNS record changes is a snapshot-and-diff loop on top of dig and the SOA serial. The hard part is not the detection, it is filtering the false positives from GeoDNS, round-robin, and CDN IP rotation so you only alert on changes that matter.
DNS monitoring catches the silent failures an uptime check never shows: records pointing at the wrong server, nameservers out of sync, expired DNSSEC signatures, broken email records. Here is exactly what it catches, what it cannot, and how to start with dig.