Section: 28.3.2.2 N3IWF FQDN 28.3.2.2.1 General
Content: The N3IWF Fully Qualified Domain Name (N3IWF FQDN) shall be constructed using one of the following formats, as specified in clause 6.3.6 of 3GPP TS 23.501[ System architecture for the 5G System (5GS) ]  [119]: - Operator Identifier based N3IWF FQDN; - Tracking Area Identity based N3IWF FQDN; - the N3IWF FQDN configured in the UE by the HPLMN. - SNPN Identifier based N3IWF FQDN. NOTE 1: If the N3IWF FQDN is configured in the UE by HPLMN, it can have a different format than those specified in the following clauses. The actual format is out of 3GPP scope. The Visited Country FQDN for N3IWF is used by a roaming UE to determine whether the visited country mandates the selection of an N3IWF in this country. The Visited Country FQDN for N3IWF shall be constructed as specified in clause 28.3.2.2.4. The Replacement field used in DNS-based Discovery of regulatory requirements shall be constructed as specified in clause 28.3.2.2.5.1. The Visited Country FQDN for SNPN N3IWF is used by a UE in the visited country to determine whether the visited country mandates the selection of an N3IWF in this country for the SNPN identified by the SNPN Identifier provided by the UE. The Visited Country FQDN for SNPN N3IWF shall be constructed as specified in clause 28.3.2.2.6. The Replacement field used in DNS-based Discovery of SNPN N3IWF for regulatory requirements shall be constructed as specified in clause 28.3.2.2.7.2. The Visited Country FQDN for N3IWF supporting Onboarding is used by a UE in the visited country to determine whether the visited country mandates the selection of an N3IWF in this country for onboarding services. The Visited Country FQDN with N3IWF supporting Onboarding shall be constructed as specified in clause 28.3.2.2.4.3. The Replacement field used in DNS-based Discovery of regulatory requirements shall be constructed as specified in clause 28.3.2.2.5.3. The Visited Country FQDN for SNPN N3IWF supporting Onboarding is used by a UE in the visited country to determine whether the visited country mandates the selection of an SNPN N3IWF in this country for onboarding services. The Visited Country FQDN with SNPN N3IWF supporting Onboarding shall be constructed as specified in clause 28.3.2.2.6.2. The Replacement field used in DNS-based Discovery of SNPN N3IWF for regulatory requirements shall be constructed as specified in clause 28.3.2.2.7.2 NOTE 2: The DNS can be configured to return no records for the visited country regardless of the SNPN ID provided by the UE. This addresses the scenario that the visited country in general does not mandate selection of a local N3IWF.