Author: Government Digital Service

Domains knowledge base

Remediation guidance

Name server and zone issues

Name servers with private IPs

Name servers that don’t provide A record for target domain name

Name servers with invalid domain names

Glue is required but not provided. No IPv4/IPv6 glue found on some authoritative or parent name servers

Name servers not allowing TCP connections to be found

Domain’s name server number doesn’t meet recommendations

Dangling resources

DNS hijacking using a non-responding name server

Expired MX or NS

Domain pointing to non-existing page on a service

Potential subdomain takeover

CNAME chain ends in NXDOMAIN

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