DNS record lookup
Query a specific record type through the DNS resolver configured for this web server. Results can reflect recursive caching and are not equivalent to querying an authoritative server directly.
What this DNS Lookup actually queries
This page uses the DNS facilities available to PHP on the web server. The query is normally handled through the resolver configured for that server, which may be recursive and may return cached information. For that reason, this tool is useful for practical inspection but should not be described as a direct authoritative DNS query unless the resolver itself is specifically configured that way.
A records carry IPv4 addresses; AAAA records carry IPv6 addresses
An A resource record maps a DNS name to an IPv4 address. AAAA is the corresponding resource record for IPv6 addresses. A hostname can publish multiple A or AAAA records, and DNS alone does not imply that every returned address has identical reachability, service state or routing behavior.
MX priority: lower numbers are preferred first
MX records identify mail exchangers for a domain and include a preference value. Lower preference numbers have higher priority. Multiple MX records with equal preference can be used by senders according to mail-routing rules; an MX lookup does not test SMTP connectivity or prove that mail delivery is working.
NS and SOA describe different parts of DNS authority
NS records identify name servers associated with DNS delegation or a zone. The SOA record contains zone-management information such as the primary server name, responsible mailbox representation, serial number and refresh, retry and expire timers. These records are especially useful when diagnosing delegation and zone-update problems.
CNAME creates a DNS alias, not an HTTP redirect
A CNAME record points an alias name to a canonical DNS name. This happens at the DNS layer. It does not instruct a web browser to change the URL and should not be confused with HTTP 301 or 302 redirects.
TXT records are generic text containers used by many protocols
TXT records can contain arbitrary text strings and are reused by several Internet mechanisms. SPF policies are commonly published in TXT records, and domain-verification systems frequently use TXT as well. DKIM public keys also commonly appear below selector-specific DNS names. A TXT lookup only displays the published data; it does not validate an entire email-authentication policy.
CAA expresses which Certificate Authorities are authorized to issue
CAA is a DNS resource record used by a domain holder to express which Certification Authorities are authorized to issue certificates for that domain. RFC 8659 defines the current CAA processing model and obsoletes RFC 6844. CAA is an issuance-control signal for CAs; it is not a replacement for certificate validation by clients.
PTR performs reverse DNS from an IP address
For IPv4, reverse DNS uses the in-addr.arpa namespace. IPv6 reverse DNS uses ip6.arpa with the address represented at nibble boundaries. This tool builds the reverse query name and requests PTR records through DNS. A PTR result maps an address back to a DNS name, but it does not by itself prove forward-confirmed reverse DNS or ownership of the returned hostname.
TTL explains caching, but the displayed value may already be counting down
TTL is the time-to-live associated with a DNS resource record for caching purposes. When PHP receives a record from a caching resolver, the TTL exposed by the resolver can represent the remaining cache lifetime rather than the original authoritative TTL. Therefore, seeing a lower TTL here does not necessarily mean the zone is configured with that exact original value.
One DNS lookup cannot prove global propagation
DNS is distributed. Recursive resolvers can hold different cached versions until their cached data expires, and delegation changes can introduce additional layers of caching. For a serious propagation investigation, compare the authoritative name servers with multiple independent recursive resolvers and verify that the delegation itself is correct.
“No record returned” is not always the same as “domain does not exist”
A DNS name can exist while having no resource record of the requested type. For example, a hostname may have an A record but no AAAA record. This PHP-based lookup does not expose every DNS response-code detail needed to reliably distinguish all failure and negative-answer cases, so the interface deliberately avoids claiming NXDOMAIN merely because the selected record type returned no records.
Internationalized domain names are converted before the DNS query when possible
When the PHP Intl extension is available, this tool converts an internationalized domain name to its ASCII-compatible DNS representation before querying it. The displayed Punycode form helps distinguish the human-readable Unicode name from the actual ASCII label sent to the DNS resolver.