Hello,
AI_ADDRCONFIG was added in order to optimise DNS query traffic, so that only useful addresses are queried for. In other words, an IPv4-only node should not query its upstream resolver for IN AAAA resource records, while an IPv6-only node should not query for IN A resource records.
The proper function of AI_ADDRCONFIG requires that: 1. The usual processing of all node-local and link-local names and addresses is preserved as long as the respective addresses are present. 2. The global name resolution is not affected by the existence or non-existence of node-local and link-local addresses. 3. IN AAAA DNS queries should not be transmitted from a node with no global IPv6 address, and vice versa: IN A queries should not to be transmitted from a node with no global IPv4 address. Unfortunately, the current implementation of getaddrinfo() mostly follows the informational RFC 3493, which fails in both #1, #2, and partially in #3.
https://fedoraproject.org/wiki/QA/Networking/NameResolution/ADDRCONFIG?rd=Ne...
https://pagure.io/SSSD/sssd/issue/1665
I believe sssd as of now doesn't keeps strong hold of pre-conditions of using AI_ADDRCONFIG.
sssd-devel@lists.fedorahosted.org