Reverse DNS Lookup
輸入 IP 地址查詢對應的主機名稱（PTR 記錄）
8.8.8.8
1.1.1.1
208.67.222.222
9.9.9.9
查詢中...
IP 地址
-
主機名稱
-
PTR 記錄
-
組織
-
ISP
-
Frequently Asked Questions
What is reverse DNS?
Reverse DNS maps an IP address back to a hostname using PTR records in the in-addr.arpa domain.
Why is it important?
Email servers check rDNS to verify sender legitimacy. Missing rDNS can cause spam flagging.
How to set it up?
Contact your ISP or hosting provider to configure PTR records for your IP addresses.
Why is reverse DNS important for email delivery?
Mail servers check if your sending IP has a valid PTR record matching your mail server hostname. Missing or mismatched reverse DNS causes emails to be flagged as spam or rejected entirely.
How do I set up a PTR record for reverse DNS?
Contact your hosting provider or ISP to set up PTR records, as only the IP block owner can create them. For cloud servers (AWS, GCP), use the provider's console to configure reverse DNS.
什麼是反向 DNS？
反向 DNS（Reverse DNS）是將 IP 地址轉換為主機名稱的過程，與一般 DNS 查詢（主機名稱轉 IP）相反。
PTR 記錄：反向 DNS 使用 PTR（Pointer）記錄。例如，IP 8.8.8.8 的反向 DNS 查詢會查找 8.8.8.8.in-addr.arpa 的 PTR 記錄。
用途：驗證郵件伺服器身份、安全性檢查、網路診斷、日誌分析等。