Lame Delegation

1. What is Lame Delegation?

One delegation is considered lame when the DNS server responsible for reverse resolution of some network does not answer with authority for that reserve zone when queried for SOA (Start of Authority).

The not authoritative answer to this query might have errors or other kind of response but the expected one from server with authority for a DNS zone.

 

2. Which are the responses the verification system might indicated in their Lame delegation checking?

AA - Authoritative Answer

This is not a error message and indicates that the DNS server has information about the domain or reverse zone in their local configuration files, i.e., this is a correctly configured server with authority for the domain or reverse zone.

TIMEOUT

No DNS query response received during the expected time.

NOAA - No Authoritative Answer

The server has information about domain or reverse zone but not from its configuration file and have learn it from another DNS server. So, this information can not be trusted.

UDN - Unknown domain name

The DNS server has no information about the domain or reverse zone it was queried about.

UH - Unsown host

The DNS server registered in LACNIC system as responsible for some network reverse resolution was not found in the Internet or it does not exist.

FAIL

A failure occurred during the communication with the DNS server.

QREFUSED - Query refused

The DNS query was refused by the server.

CREFUSED - Connection Refused

The DNS connection was refused by the server. It might had happened because there was no DNS program running on this server.

CNAME - Canonical Name

The DNS server name registered in LACNIC system is not the real name of the server but a alias, what is a not recommend practice.

NOT SYNC ZONE - Not synchronized zone

The reverse zone configuration version in one of the DNS servers is different from the version in the others servers responsible for the same reverse zone.

 

3. Where can I find more information about DNS server configuration?

You can find more information about DNS server configuration at the following sites:

Or at the literature bellow:

  • P. Albitz, C. Liu, "DNS and BIND, 4th. edition", OReilly & Associates, Inc. - ISBN: 0596001584

Obs.: At the link bellow it is possible to check Lame Delegation statistics related to address space under LACNIC responsibility.

http://lacnic.net/en/lame_delegation.html