All the requests sent from Uptime Robot are using pre-defined IPs to make sure that we all know the source of the requests.
A new IP block is being added to the system:
And, if exists, please make sure it is whitelisted in your firewalls.
Also, the full list of the IPs used can be found here.
P.S.> If you had never needed to whitelist or take action regarding to Uptime Robot’s IPs in the past, then you probably don’t need to take any action and can ignore this info.