Technical guides on reverse DNS management, PTR records, email deliverability, and IPv6 rDNS for ISPs and data centers.
Missing or misconfigured PTR records are one of the leading causes of email landing in spam folders - or being rejected outright. Learn what reverse DNS is, why major mail providers check it, and what consequences ISPs face when PTR records are absent or incorrect.
Read article →When you operate hundreds of IP blocks across multiple customers, managing PTR records manually becomes a liability. This guide covers the real-world challenges ISPs face at scale and how API-driven rDNS management changes the equation.
Read article →IPv6 reverse DNS operates on a fundamentally different scale than IPv4 - a single /48 allocation contains 280 trillion addresses. This guide covers ip6.arpa zones, delegation from regional registries, and what automation is required to stay on top of it.
Read article →An ISP holds its in-addr.arpa zones on delegation from its RIR, not by ownership. This guide covers how RIPE NCC, ARIN, and APNIC each hand off delegation, why zone cuts land on /24 boundaries, and how RFC 2317 delegates smaller blocks.
Read article →Understanding ip6.arpa zone structure is one problem; keeping IPv6 PTR records correct on an ongoing basis is another. This guide covers the automation architectures - GitOps, dynamic updates, API-driven provisioning - that replace manual management.
Read article →Missing PTR is one failure mode. A present but generic PTR record is another. This guide covers how FCrDNS validation actually runs and what ISPs should provision by default for residential, business, and mail-sending IPs.
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