Why do I need to register DNS servers for the blocks assigned to my organization?

DNS delegation for IP address blocks allows reverse resolution, i.e. finding out the name associated with an IP address that is being used by a computer.

How can I enter or modify the DNS servers to provide reverse resolution for an IP address block?

In addition to managing Internet number resources for Latin America and the Caribbean, LACNIC is also responsible for global reverse resolution. To delegate a block’s reverse resolution, go to https://milacnic.lacnic.net/lacnic/login and login with the userID of your Organization's administrative contact. Once you have logged in, go to the “IP/ASN” section located to the left of the menu and identify the IPv4 or IPv6 block you wish to delegate. Note that you must select the parent block you have been assigned of which the block you wish to delegate is a part. If you would like to delegate the entire block, in this case 201.219.252/22, click on “Delegate (rDNS).” The system will show the ranges available for delegation. On the following screen you must specify the range you would like to delegate and enter the servers responsible for the block’s reverse DNS resolution. Bear in mind that each Class C that makes up this /22, in this case the four /24s, must be properly configured on your server.

If you would like to delegate a smaller block, such as, for example, the first /24 corresponding to this /22, you will have to complete the same process, except that on the screen prior to entering the name of the servers you must specify the /24 range for which you want to enter the delegation.

To modify reverse resolution servers that have already been delegated, click the “Edit” button in the “Delegate (rDNS)” section and change the name of the servers. Note that you must enter the host names of the servers, not their IP addresses.

Detailed instructions on this topic are available at the following link: https://lacnic.zendesk.com/hc/es/articles/231543267-Delegar-DNS-reverso-rDNS-para-Bloque-IP-parte-1-

What do the "Lame Delegation" messages I receive mean?

A "Lame Delegation" means that a DNS delegation has problems. This happens when the information on the IP address block in the DNS server registered in the database is not accurate, or when the DNS server can't be accessed by LACNIC's monitoring system and, therefore, causes reverse resolution errors. You should check your DNS server configuration.

How can I check the status of the DNS servers responsible for reverse resolution?

LACNIC's WHOIS server reports the status of the IP address blocks' DNS delegation and which servers are configured to respond to that assignment.

This information is available in the "nserver", "nsstat" and "nslastaa" fields of the responses provided by the WHOIS server when querying by IP address block.

The "nserver" field specifies which DNS server must respond to the delegation, the "nsstat" field specifies the delegation's status, and the "nslastaa" field specifies the date on which a correct configuration was observed on this server. To verify that your server is responding with the right information you can perform a test using the "dig" application. You should receive a "NOERROR" response. "NXDOMAIN" or "SERVFAIL" responses mean that there is a configuration error in your DNS server.

dig soa @nserver delegacion.in-addr.arpa

dig soa @NS.LACNIC.NET 80.7.200.in-addr.arpa


Why do I get a system error when trying to register my DNS servers?

This can occur when the DNS servers specified in the system are not yet properly configured for the reverse resolution of an IP address block.

The DNS server must have information on every network that makes up the IP address block. For example, in the case of a /20, the server must have information on the 16 /24 networks it comprises. To check your DNS, follow the recommendations specified in the previous question.