Reverse DNS
Resolving an IP address to a name using PTR records. Address-space operators usually control it; matching reverse DNS alone does not authenticate email senders.
Definition and sourcesKNOWLEDGE / FROM A TO Z
Glossary
Technology, explained clearly. Find a term, choose a letter or narrow the topic. Definitions include sources and their review date.
Terms 32 / 685
Clear filtersServer Name Indication
A TLS extension transmitting the server name during connection establishment. It helps select a certificate on shared addresses and is not a DNS record.
Definition and sourcesSplit-horizon DNS
DNS returning different data according to query source or view. Useful internally, it complicates diagnosis and configuration consistency.
Definition and sourcesSubdomain
A name below another in the DNS hierarchy, such as blog.example.com under example.com. It may have separate delegation or services and is not a website folder.
Definition and sourcesTime to live
A value limiting cached-data lifetime, such as a DNS record's. It does not guarantee simultaneous resolver refreshes; the term has other networking meanings too.
Definition and sourcesTLD (Top-Level Domain)
The final part of a domain name, such as .pl or .com. Categories include country-code and generic TLDs. An ending alone establishes neither owner trustworthiness nor improved search rankings.
Definition and sourcesWHOIS and RDAP
Mechanisms querying internet-resource registration data. RDAP replaces some WHOIS uses; public-data coverage depends on registry and privacy rules.
Definition and sourcesWildcard DNS
Records using a * label to synthesise answers for certain missing names. They do not simply match every address or replace wildcard certificates.
Definition and sources