1. A computer-implemented method to manage security policy propagation between a plurality of domains of secured computing systems and based on a policy-specific propagation flag and a domain-specific inheritance rule, the method comprising: applying a security policy to a parent domain that includes a first secured computing system, wherein the security policy specifies a propagation flag that is policy-specific and not domain-specific and that indicates whether the security policy is to be propagated or isolated; upon determining that the parent domain propagates the security policy on the basis of the propagation flag, identifying a child domain that includes a second secured computing system and that is associated with the parent domain in a hierarchical relationship specifying an inheritance rule that is domain-specific and not policy-specific and that indicates whether security policy propagation applies from the parent domain to the child domain, wherein the child domain is associated with a grandchild domain; and upon determining that the inheritance rule includes a first rule code indicating that security policy propagation applies from the parent domain to the child domain, applying the security policy to the child domain by operation of one or more computer processors; wherein the security policy is not applied to the child domain and not applied to the grandchild domain if the inheritance rule includes a second rule code indicating that security policy propagation is stopped at the child domain; wherein the security policy is not applied to the child domain but applied to the grandchild domain if the inheritance rule includes a third rule code indicating that security propagation is bypassed at the child domain; wherein the security policy is managed based on at least one of: (i) a domain hierarchy specification including the hierarchical relationship; (ii) a domain policy assignment specification including the domain-specific inheritance rule; and (iii) a security policy propagation specification including the policy-specific propagation flag.