Updated Implementation Date for Changes to the IESOs Digital Certificate Authority
September 11, 2025
The IESO’s certificate authority, DigiCert, re-scheduled two important changes that may impact connectivity with the IESO’s website and systems, including the public reports site, Market Information Management (MIM) system, Dispatch Service, and Online IESO. Firstly, DigiCert will be adding a secondary content delivery network with additional dedicated IPv4 addresses to support specific DigiCert services. Secondly, DigiCert will be ending support for HTTP/1.0 connections. These changes have been re-scheduled for September 22 at 12:00 p.m. EDT.
A reminder that stakeholders who use allowlists to control their outbound traffic will need to include the following IPv4 addresses:
- 162.159.142.7
- 162.159.142.8
- 162.159.142.9
- 162.159.142.10
- 172.66.2.3
- 172.66.2.4
- 172.66.2.5
- 172.66.2.6
Stakeholders that connect to the IESO using HTTP/1.0 for certificate status verification will need to upgrade their protocol to HTTP/1.1 or later.
These changes will need to be performed before September 22 to avoid potential disruptions or connectivity issues to the IESO website or systems.
For more information, please contact IESOCustomerRelations@ieso.ca.