The reverse DNS entries and IP addresses that Web Check uses to monitor your assets are:

• check.check-stage.webcheck.service.ncsc.gov.uk 63.34.195.6
• check1.check-stage.webcheck.service.ncsc.gov.uk 54.155.77.11

Further information on Web Check can be found here. If you have any additional queries please contact feedback@digital.ncsc.gov.uk.