I was getting > 30sec to complete "sudo su" on a host. This host had
invalid entries in resolv.conf and I realized sudo was doing 5 seconds
lookup on each entry searching for "localhost.localdomain"
sudo is 1.8.19p1 @ stretch.
Believe no DNS lookups should be made... even for localhost
sendmmsg(6, [{msg_hdr={msg_name=NULL, msg_namelen=0,
msg_iov=[{iov_base="\372\251\1\0\0\1\0\0\0\0\0\0\tlocalhost\vlocaldoma"...,
iov_len=39}], msg_iovlen=1, msg_controllen=0, msg_flags=MSG_OOB|MSG_PEEK},
msg_len=39}, {msg_hdr={msg_name=NULL, msg_namelen=0,
msg_iov=[{iov_base="\25\201\1\0\0\1\0\0\0\0\0\0\tlocalhost\vlocaldoma"...,
iov_len=39}], msg_iovlen=1, msg_controllen=0, msg_flags=MSG_PEEK},
msg_len=39}], 2, MSG_NOSIGNAL) = 2
sendmmsg(6, [{msg_hdr={msg_name=NULL, msg_namelen=0,
msg_iov=[{iov_base="\372\251\1\0\0\1\0\0\0\0\0\0\tlocalhost\vlocaldoma"...,
iov_len=39}], msg_iovlen=1, msg_controllen=0, msg_flags=MSG_OOB|MSG_PEEK},
msg_len=39}, {msg_hdr={msg_name=NULL, msg_namelen=0,
msg_iov=[{iov_base="\25\201\1\0\0\1\0\0\0\0\0\0\tlocalhost\vlocaldoma"...,
iov_len=39}], msg_iovlen=1, msg_controllen=0, msg_flags=MSG_PEEK},
msg_len=39}], 2, MSG_NOSIGNAL) = 2
sendmmsg(6, [{msg_hdr={msg_name=NULL, msg_namelen=0,
msg_iov=[{iov_base="\313\265\1\0\0\1\0\0\0\0\0\0\tlocalhost\vlocaldoma"...,
iov_len=51}], msg_iovlen=1, msg_controllen=0, msg_flags=MSG_OOB|MSG_PEEK},
msg_len=51}, {msg_hdr={msg_name=NULL, msg_namelen=0,
msg_iov=[{iov_base="\1\371\1\0\0\1\0\0\0\0\0\0\tlocalhost\vlocaldoma"...,
iov_len=51}], msg_iovlen=1, msg_controllen=0, msg_flags=MSG_PEEK},
msg_len=51}], 2, MSG_NOSIGNAL) = 2
sendmmsg(6, [{msg_hdr={msg_name=NULL, msg_namelen=0,
msg_iov=[{iov_base="\313\265\1\0\0\1\0\0\0\0\0\0\tlocalhost\vlocaldoma"...,
iov_len=51}], msg_iovlen=1, msg_controllen=0, msg_flags=MSG_OOB|MSG_PEEK},
msg_len=51}, {msg_hdr={msg_name=NULL, msg_namelen=0,
msg_iov=[{iov_base="\1\371\1\0\0\1\0\0\0\0\0\0\tlocalhost\vlocaldoma"...,
iov_len=51}], msg_iovlen=1, msg_controllen=0, msg_flags=MSG_PEEK},
msg_len=51}], 2, MSG_NOSIGNAL) = 2
