Practical guides on DNS records, propagation, and keeping your domains healthy.
DNS Infrastructure
Most domains give everyone the same answer no matter where the query comes from. Split-horizon DNS deliberately doesn't: the same hostname resolves to a different address depending on whether the query originates inside or outside the network.
Product Guide
The default monitoring interval is built for the vast majority of records that rarely change. Frequent Monitoring exists for the small number that can't wait an hour, checking a limited set of priority hosts every 5 minutes instead.
Product Guide
Muting a host's record type stops it from raising alerts or sending notifications, either indefinitely or for a fixed window, without turning off monitoring or hiding the change from your history.
DNS Infrastructure
Azure DNS hands you nameservers on four different TLDs, not four servers under the same one. That's deliberate. Here's the specific failure mode TLD diversity protects against, and why not every major provider bothers with it.
DNS Infrastructure
Domains typically run on multiple nameservers for redundancy, which raises an obvious question: how do the copies stay in sync. AXFR, IXFR, and NOTIFY are the mechanisms behind it, and why an open zone transfer is a real information-disclosure risk.
DNS Records
CNAME records can't be used at a domain's apex, but pointing a bare domain at a CDN or hosting platform that only gives you a hostname is a common need. ALIAS and ANAME records are how most DNS providers solve it, and how they actually work behind the scenes.
DNS Records
Most DNS records answer "where does this name point." SRV records answer a more specific question: which host and port handles a particular service. Here's the format, where SRV actually gets used, and why most web traffic never touches it.
DNS Infrastructure
The record-specific articles on this blog assume you already know how a DNS lookup happens. This one explains it from the ground up: what a domain name is made of, how a query travels from your browser to an authoritative nameserver, and the vocabulary behind everything else in DNS.
Email Authentication
DMARC just left Informational status after eleven years and moved onto the IETF Standards Track, split across three RFCs. Here's what RFC 9989, 9990, and 9991 actually change, what they deprecate, and what a domain owner needs to do about it (mostly nothing, with two exceptions).
DNS Records
Every other DNS record answers 'what's the IP for this name.' A PTR record answers the opposite question, and it's controlled by whoever owns the IP address, not whoever owns the domain. Here's how reverse DNS works and why mail servers care so much about it.