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Are LLMNR queries always sent when DNS fails?

April 26, 2017DNS fails llmnr queries sent

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Are LLMNR queries always sent when DNS fails?

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No. LLMNR is a name resolution protocol of last resort. LLMNR queries MAY only be sent if a DNS server is not configured, or if DNS queries are sent first, exhausting the search list. However, these conditions are NOTsufficient – an LLMNR implementation need not send LLMNR queries even if these conditions are satisfied. An implementation may further restrict the conditions under which LLMNR queries are sent. For example, when a DNS server is configured, an implementation may choose to only send LLMNR queries for unqualified names (e.g. “fred”) or for names within configured zones (e.g. if the default domain is “example.com”, only send queries for “foo.example.com” or “foo.bar.example.com” but not “foo.com”).