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Networking Fundamentals · Intermediate

Reverse DNS Lookup (rDNS)

Resolving an IP address back to a host name by querying PTR records.

Definition

The address is reversed and appended to in-addr.arpa (or written nibble by nibble under ip6.arpa) for the query. Logs and security tools use reverse lookups to identify hosts.

Example

nslookup 8.8.8.8 returns dns.google.

Exam tip

Reverse lookups require PTR records in a reverse zone.

Related terms