$ gpg-connect-agent --dirmngr 'getinfo dnsinfo' /bye
OK - Libdns stub resolver

$ gpg --debug-level guru --search-keys CEB167EFB5722BD6
$ cat dirmngr.log
2018-01-08 20:06:37 dirmngr[1085.0] permanently loaded certificates: 141
2018-01-08 20:06:37 dirmngr[1085.0]     runtime cached certificates: 0
2018-01-08 20:06:37 dirmngr[1085.0]            trusted certificates: 141 (140,0,0,1)
2018-01-08 20:06:37 dirmngr[1085.6] handler for fd 6 started
2018-01-08 20:06:37 dirmngr[1085.6] DBG: chan_6 -> # Home: /home/walz/.gnupg
2018-01-08 20:06:37 dirmngr[1085.6] DBG: chan_6 -> # Config: /home/walz/.gnupg/dirmngr.conf
2018-01-08 20:06:37 dirmngr[1085.6] DBG: chan_6 -> OK Dirmngr 2.2.4 at your service
2018-01-08 20:06:37 dirmngr[1085.6] connection from process 1084 (1000:100)
2018-01-08 20:06:37 dirmngr[1085.6] DBG: chan_6 <- GETINFO version
2018-01-08 20:06:37 dirmngr[1085.6] DBG: chan_6 -> D 2.2.4
2018-01-08 20:06:37 dirmngr[1085.6] DBG: chan_6 -> OK
2018-01-08 20:06:37 dirmngr[1085.6] DBG: chan_6 <- KS_SEARCH -- CEB167EFB5722BD6
2018-01-08 20:06:37 dirmngr[1085.6] DBG: dns: libdns initialized
2018-01-08 20:06:37 dirmngr[1085.6] DBG: dns: getsrv(_pgpkey-https._tcp.hkps.pool.sks-keyservers.net) -> 0 records
2018-01-08 20:06:37 dirmngr[1085.6] DBG: dns: resolve_dns_name(hkps.pool.sks-keyservers.net): No name
2018-01-08 20:06:37 dirmngr[1085.6] resolving 'hkps.pool.sks-keyservers.net' failed: No name
2018-01-08 20:06:37 dirmngr[1085.6] number of system provided CAs: 156
2018-01-08 20:06:37 dirmngr[1085.6] DBG: dns: resolve_dns_name(hkps.pool.sks-keyservers.net): No name
2018-01-08 20:06:37 dirmngr[1085.6] resolving 'hkps.pool.sks-keyservers.net' failed: No name
2018-01-08 20:06:37 dirmngr[1085.6] can't connect to 'hkps.pool.sks-keyservers.net': host not found
2018-01-08 20:06:37 dirmngr[1085.6] error connecting to 'https://hkps.pool.sks-keyservers.net:443': No name
2018-01-08 20:06:37 dirmngr[1085.6] command 'KS_SEARCH' failed: No name
2018-01-08 20:06:37 dirmngr[1085.6] DBG: chan_6 -> ERR 167772380 No name <Dirmngr>
2018-01-08 20:06:37 dirmngr[1085.6] DBG: chan_6 <- BYE
2018-01-08 20:06:37 dirmngr[1085.6] DBG: chan_6 -> OK closing connection
2018-01-08 20:06:37 dirmngr[1085.6] handler for fd 6 terminated