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Part of HSCN domain naming standards and policies

PTR records in a reverse-lookup zone

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Reverse-lookup zone (ARPA zone)

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PTR records

A PTR record in a reverse-lookup (ARPA) zone is a pointer to a record in forward-lookup zone. It permits an IP address to be looked up to return a hostname.

The following standards apply.

  1. PTR records can only be requested in ARPA zones.
  2. PTR records on the internet can only be requested within subnets actually assigned to NHS England by RIPE and configured on the HSCN DNS Service - requests for PTR records in non-NHS England-assigned subnets must be directed to the assignee.
  3. PTR records on HSCN can only be requested within subnets in use on HSCN and configured on the HSCN DNS Service.

Lifecycle

PTR records must be reviewed regularly, and removed immediately they are no longer required, or when the target is no longer resolvable.

Unused PTR records will be removed without notice.

Last edited: 11 June 2024 12:05 pm

Chapters

  1. HSCN domain naming standards and policies
  2. Management
  3. Domain and record naming
  4. Hierarchy
  5. Records in the apex domains
  6. Sub-domain of the apex domains
  7. Records in a sub-domain
  8. Off-infrastructure delegation of sub-domains
  9. Records with an off-infrastructure target
  10. Reverse-lookup zone (ARPA zone)
  11. PTR records in a reverse-lookup zone