Server & Network

ASN/IP Intelligence & Blacklist Inquiry

By entering an IP address or domain, you can get free ASN information, datacenter/ISP name, country and city location, rDNS record, and the status of 5 different DNSBL blacklists.

ASN/IP Intelligence & Blacklist Inquiry
Information

About ASN/IP Intelligence & Blacklist Inquiry

Identifying an IP address or domain name on the internet is critical in many areas, including network security, identifying spam sources, verifying server location, and improving email delivery. This tool retrieves the ASN (Autonomous System Number), ISP/datacenter name, geographic location (country, city), and reverse DNS (rDNS) record for the IP or domain you enter in a single query.

In addition, the tool automatically checks the IP address against five different DNSBL (DNS-based Blacklist) databases: Spamhaus ZEN, SpamCop, Barracuda, SORBS and CBL (Abuseat)These lists contain IP addresses that have been associated with malicious behavior, such as sending spam, distributing malware, or engaging in botnet activity. Checking this list is the right starting point if you are experiencing delivery problems with your email server or suspect your server is blocked.

When you enter a domain name, the tool first resolves the DNS A record to find the IP address; then it performs all analyses using that IP address. Only public IPv4 addresses are supported; private network and local addresses are rejected for security reasons. All queries are performed on the server side; results are displayed simply with "Clean" or "Listed" badges.

How to use it?

Step by step

  1. What you want to inquire about IP address (e.g. 8.8.8.8) or domain name (e.g. example.comEnter )
  2. Inquire Click the button or press Enter.
  3. On the ASN / Datacenter card Check the ASN number, ISP/org name, country, city, and rDNS record.
  4. DNSBL Blacklist table for each list Clean or On the list See the badge.
  5. If your site is listed, initiate the delisting process by visiting the relevant listing provider's website.
FAQ

Frequently Asked Questions

An ASN (Autonomous System Number) is a unique number assigned to an IP address block on the internet, controlled by an independent network administrator. Every major ISP, data center, and large organization has its own ASN. Knowing which ASN an IP belongs to is important for understanding which service provider infrastructure that IP is running on, whether it belongs to an ASN with a history of spam/abuse, and for identifying traffic routing issues.

DNSBL (DNS-Based Blackhole List) are DNS-based databases that publish IP addresses identified as exhibiting malicious activity. Email servers check the source IP of incoming messages against these lists; emails from IPs on the list usually end up in the spam folder or are rejected altogether. Being on the list most often means sending spam, botnet infection, or abuse; however, it can sometimes be a false positive.

Each DNSBL has its own delisting process. First, investigate why you were listed: there might be spamming software on your server, an open relay, or an infected device. After taking steps to resolve the issue, submit a delisting request from the relevant listing's website (e.g., spamhaus.org, spamcop.net). Some listings perform automatic delisting, while others require review.

When you enter a domain name, the tool retrieves the first public IPv4 address from that domain's DNS A record and performs all checks (ASN query + DNSBL) using that IP. If there are multiple A records, the first public IP is used. The results page shows which IP was queried.

rDNS (Reverse DNS/PTR record) holds the domain name corresponding to an IP address. Many email servers check whether the source IP of incoming messages has a valid and consistent PTR record; a missing or inconsistent rDNS record increases the risk of being classified as spam. Ensure your rDNS record is correctly configured to optimize your server infrastructure.
Return to all free tools