SC-21—Secure Name/Address Resolution Service (Recursive Or Caching Resolver)
LOW
MODERATE
HIGH
>Control Description
Request and perform data origin authentication and data integrity verification on the name/address resolution responses the system receives from authoritative sources.
>Control Enhancements(1)
>Cross-Framework Mappings
>Programmatic Queries
Beta
Related Services
Route 53 Resolver
VPC DNS
DNS Firewall
CLI Commands
List Route 53 Resolver endpoints
aws route53resolver list-resolver-endpoints --query 'ResolverEndpoints[*].{Id:Id,Name:Name,Direction:Direction,Status:Status}'Check DNS Firewall rules
aws route53resolver list-firewall-rule-groupsList resolver rules
aws route53resolver list-resolver-rules --query 'ResolverRules[*].{Id:Id,Name:Name,RuleType:RuleType}'Check DNSSEC validation
aws route53resolver list-resolver-dnssec-configs>Supplemental Guidance
Each client of name resolution services either performs this validation on its own or has authenticated channels to trusted validation providers. Systems that provide name and address resolution services for local clients include recursive resolving or caching domain name system (DNS) servers. DNS client resolvers either perform validation of DNSSEC signatures, or clients use authenticated channels to recursive resolvers that perform such validations.
Systems that use technologies other than the DNS to map between host and service names and network addresses provide some other means to enable clients to verify the authenticity and integrity of response data.
>Related Controls
>Assessment Interview Topics
Questions assessors commonly ask
Process & Governance:
- •What policies govern the implementation of secure name/address resolution service (recursive or caching resolver)?
- •How are system and communications protection requirements defined and maintained?
- •Who is responsible for configuring and maintaining the security controls specified in SC-21?
Technical Implementation:
- •How is secure name/address resolution service (recursive or caching resolver) technically implemented in your environment?
- •What systems, tools, or configurations enforce this protection requirement?
- •How do you ensure that secure name/address resolution service (recursive or caching resolver) remains effective as the system evolves?
- •What network boundary protections are in place (firewalls, gateways, etc.)?
Evidence & Documentation:
- •What documentation demonstrates the implementation of SC-21?
- •Can you provide configuration evidence or system diagrams showing this protection control?
- •What logs or monitoring data verify that this control is functioning correctly?
- •Can you provide network architecture diagrams and firewall rulesets?
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