R1DNS - Free DNS Testing Tools

DNSCheck

Test a domain for proper DNS configuration. Verifies matching NS records at each nameserver, checks for non-authorative delegation, unlisted name servers, matching A record responses and unresponsive / misconfigured DNS servers. NS queries are done directly without caching, so any changes should be reflected immediately. Recursive cached lookups are used for glue and A records.

PTRCheck

Test a PTR lookup of an IP address. Shows delegation and verifies forward lookup.