DNS/hijacking/SubdomainTakeover/hostileについて、ここに記述してください。

Types of services you create subdomains to use are:

    a shopping cart for your ecommerce website,
    a ticketing system like ServiceNow,
    a CDN
    Various cloud platforms
    Externally hosted subdomain based websites
    and so on

A hostile subdomain takeover‍ means that an attacker registers with the service you used but no longer use and register to use your abandoned subdomain.