Chapter 99. Updating DNS records systematically when using external DNS When using external DNS, Identity Management (IdM) does not update the DNS records automatically after a change in the topology. You can update the DNS records managed by an external DNS service systematically, which reduces the need for manual DNS updates. Updating DNS records removes old or invalid DNS records and adds new records. You must update DNS records after a change in your topology, for example: After installing or uninstalling a replica After installing a CA, DNS, KRA, or Active Directory trust on an IdM server 99.1. Updating external DNS records with GUI If you have made any changes to your topology, you must update the external DNS records by using the external DNS GUI. Procedure Display the records that you must update: Use the external DNS GUI to update the records. 99.2. Updating external DNS records using nsupdate You can update external DNS records using the nsupdate utility. You can also add the command to a script to automate the process. To update with the nsupdate utility, you need to generate a file with the DNS records, and then proceed with either sending an nsupdate request secured using TSIG, or sending an nsupdate request secured using the GSS-TSIG. Procedure To generate a file with the DNS records for nsupdate, use the ` ipa dns-update-system-records --dry-run command with the --out option. The --out option specifies the path of the file to generate: The generated file contains the required DNS records in the format accepted by the nsupdate utility. The generated records rely on: Automatic detection of the zone in which the records are to be updated. Automatic detection of the zone's authoritative server. If you are using an atypical DNS setup or if zone delegations are missing, nsupdate might not be able to find the right zone and server. In this case, add the following options to the beginning of the generated file: server : specify the server name or port of the authoritative DNS server to which nsupdate sends the records. zone : specify the name of the zone where nsupdate places the records. Example 99.1. Generated record 99.3. Sending an nsupdate request secured using TSIG When sending a request using nsupdate , make sure you properly secure it. Transaction signature (TSIG) enables you to use nsupdate with a shared key. Prerequisites Your DNS server must be configured for TSIG. Both the DNS server and its client must have the shared key. Procedure Run the nsupdate command and provide the shared secret using one of these options: -k to provide the TSIG authentication key: -y to generate a signature from the name of the key and from the Base64-encoded shared secret: 99.4. Sending an nsupdate request secured using GSS-TSIG When sending a request using nsupdate , make sure you properly secure it. GSS-TSIG uses the GSS-API interface to obtain the secret TSIG key. GSS-TSIG is an extension to the TSIG protocol. Prerequisites Your DNS server must be configured for GSS-TSIG. Note This procedure assumes that Kerberos V5 protocol is used as the technology for GSS-API. Procedure Authenticate with a principal allowed to update the records: Run nsupdate with the -g option to enable the GSS-TSIG mode: 99.5. Additional resources nsupdate(8) man page RFC 2845 describes the TSIG protocol RFC 3645 describes the GSS-TSIG algorithm

Commands:
ipa dns-update-system-records --dry-run IPA DNS records: _kerberos-master._tcp.example.com. 86400 IN SRV 0 100 88 ipa.example.com. _kerberos-master._udp.example.com. 86400 IN SRV 0 100 88 ipa.example.com. [... output truncated ...]
ipa dns-update-system-records --dry-run --out dns_records_file.nsupdate IPA DNS records: _kerberos-master._tcp.example.com. 86400 IN SRV 0 100 88 ipa.example.com. _kerberos-master._udp.example.com. 86400 IN SRV 0 100 88 ipa.example.com. [... output truncated ...]
cat dns_records_file.nsupdate zone example.com . server 192.0.2.1 ; IPA DNS records update delete _kerberos-master._tcp.example.com. SRV update add _kerberos-master._tcp.example.com. 86400 IN SRV 0 100 88 ipa.example.com. [... output truncated ...]
nsupdate -k tsig_key.file dns_records_file.nsupdate
nsupdate -y algorithm:keyname:secret dns_records_file.nsupdate
kinit principal_allowed_to_update_records@REALM
nsupdate -g dns_records_file.nsupdate