ICANN CZDS & TLD Zone File Directory
Authoritative technical index of top-level domain zone file access policies, uncompressed text record sizes, Centralized Zone Data Service (CZDS) approval rates, and RFC-1035 AXFR zone transfer mechanisms.
.com Zone File Size 3.9 GB 325M+ uncompressed records
Centralized CZDS Coverage 1,200+ gTLDs Unified ICANN portal
Public Root Zone AXFR Open Access xfr.cjr.dns.icann.org
Standard Renewal Cycle 90 Days Periodic researcher re-auth
How Researchers & Threat Hunters Access TLD Zone Files
Under ICANN's Base Registry Agreement (Specification 4), every contracted generic top-level domain is legally required to provide daily zone file access to accredited researchers via the Centralized Zone Data Service (czds.icann.org). Zone files contain the authoritative list of all registered domain names within the TLD and their corresponding nameserver (NS) delegations.
Direct Command to Download Official Root Zone File via AXFR:
dig @xfr.cjr.dns.icann.org . AXFR > root.zone
Research Use Cases: Threat hunting, brand infringement monitoring, new domain registration velocity tracking, and passive DNS infrastructure mapping.
Zone File Sizing & Approval Specifications
Audited CZDS & Root Zone Parameters| Namespace / TLD | Uncompressed Size | Approximate Records | CZDS Access Policy | Daily Update Frequency | Transfer Protocol | Registry Operator |
|---|---|---|---|---|---|---|
| Root Zone (.) | 2.5 MB | 15,000 NS and DS records | Auto-Approved (24h) | Twice daily or upon delegation modifications | AXFR via xfr.cjr.dns.icann.org and HTTPS download | Internet Assigned Numbers Authority (IANA / ICANN) |
| .com | 3.9 GB | 325,000,000 NS and glue records | Auto-Approved (24h) | Twice daily (06:00 and 18:00 UTC) | CZDS REST API & authenticated SFTP | Verisign, Inc. |
| .net | 320 MB | 26,000,000 records | Auto-Approved (24h) | Twice daily (06:00 and 18:00 UTC) | CZDS REST API & authenticated SFTP | Verisign, Inc. |
| .org | 250 MB | 21,000,000 records | Auto-Approved (24h) | Once daily (08:00 UTC) | CZDS REST API | Public Interest Registry (PIR) |
| .xyz | 85 MB | 7,200,000 records | Auto-Approved (24h) | Daily rolling update | CZDS REST API | Generation.XYZ / CentralNic backend |
| .info | 95 MB | 8,000,000 records | Auto-Approved (24h) | Daily (14:00 UTC) | CZDS REST API | Identity Digital |
| .app | 18 MB | 1,500,000 records | Manual Review | Daily (00:00 UTC) | CZDS REST API | Google Registry (Charleston Road) |
| .dev | 14 MB | 1,200,000 records | Manual Review | Daily (00:00 UTC) | CZDS REST API | Google Registry (Charleston Road) |
| .bank | 120 KB | 7,500 records | Strict Vetting | Real-time dynamic updates | Restricted Secure EPP & SFTP | fTLD Registry Services |