PCI DSS § 11.2 requires internal and external vulnerability scans at least quarterly and after any significant changes. The external scans must be done by a PCI Approved Scanning Vendor (ASV).
Tech Lock is a PCI ASV - click
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NIST SP800-53 § RA-5 requires scans to be conducted on a regular basis, and when new potential vulnerabilities are identified.
ISO 27002 § 12.6.1 requires that vulnerabilities be identified on a timely basis, and
§ 15.2.2 requires technical compliance checking.