Changes to IESO's Digital Certificate Authority That May Affect Access to the Website and Systems
August 21, 2025
On September 8 at 12:00 p.m. EDT, the IESO’s certificate authority, DigiCert, will be implementing two important changes that may impact your organization’s connectivity with the IESO 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.
Stakeholders who use allow lists 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 8 to avoid potential disruptions or connectivity issues to the IESO website or systems.
Please direct your inquiries to IESOCustomerRelations@ieso.ca.