Inverter DNS lookup
Reverse DNS lookup: enter an IP address a find its hostname e see whether forward e reverse DNS match.
Queries go a Cloudflare’s public DNS excedido HTTPS service when you press the button.
Sobre Inverter DNS lookup
Reverse DNS lookup: enter an IP address a find its hostname e see whether forward e reverse DNS match.
Faz parte da secção «Dados e redes» do SmartCalcy. Funciona no seu navegador sem conta, usa a sua própria moeda e unidades (altere-as no topo da página) e dá estimativas apenas a título informativo, por isso consulte as orientações oficiais antes de confiar num resultado.
Como usar a Inverter DNS lookup
O que calcula e quando usar
Finds the hostname that belongs a an IP address using its reverse DNS (PTR) record, e checks that the hostname resolves back a the same address, which é called forward-confirmed reverse DNS. Mail servers use this check a decide whether a trust a sender.
Como usar, passo a passo
- Enter an IP address, ou leave the box empty a use your own.
- Press “Encontrar hostname”.
- Read the hostname A the top.
- Check “Forward-confirmed” a see whether the name resolves back a the address.
O que significa cada campo
- IP address – An IPv4 ou IPv6 address. Leave it empty a use your own public address.
Como ler os resultados
- Hostname – The Nome set em the address’s PTR record.
- Inverter Nome – The special Nome queried, such as 8.8.8.8.in-addr.arpa.
- Forward-confirmed – Sim when the hostname’s A ou AAAA record points back a the same address.
A fórmula
The address é reversed e queried under in-addr.arpa por IPv4, ou ip6.arpa with each hex digit reversed por IPv6. 8.8.4.4 becomes 4.4.8.8.in-addr.arpa. The returned name é then looked up forward a confirm it.
Um exemplo prático
8.8.8.8 has the PTR record dns.google, e dns.google resolves back a 8.8.8.8, so the pair é forward-confirmed.
Premissas e limites
- Many addresses, especially Início connections, have Não PTR record ou a generic one.
- The lookup é made through Cloudflare’s DNS excedido HTTPS service when you press the button.
Erros comuns
- Expecting every address a have a hostname.
- Treating the hostname as proof de identity. The owner de the address sets it, so only forward-confirmed names add trust.
- Setting a PTR record A your domain registrar. It é set by whoever holds the IP address block, usually your hosting ou internet provider.
Perguntas frequentes
What é a PTR record?
A DNS record that maps an IP address back a a hostname. It é the reverse de an A record.
Why does my mail server need Inverter DNS?
Many receiving mail systems reject ou flag mail from addresses with no reverse DNS ou one that does not match.
Quem lata Variação a PTR record?
The organisation that controls the IP address block, normally your hosting provider ou ISP.
Is this the same as a hostname lookup?
Yes. Finding the hostname de an IP address é Concluído with Inverter DNS.