resolv.conf

ホスト名を書いたとき

# strace ping -c 1 www.example.com 2>&1 | grep open
open("/etc/ld.so.preload", O_RDONLY)    = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY)      = 3
open("/lib/tls/libresolv.so.2", O_RDONLY) = 3
open("/lib/tls/libc.so.6", O_RDONLY)    = 3
open("/etc/resolv.conf", O_RDONLY)      = 4
open("/etc/nsswitch.conf", O_RDONLY)    = 4
open("/etc/ld.so.cache", O_RDONLY)      = 4
open("/lib/tls/libnss_files.so.2", O_RDONLY) = 4
open("/etc/host.conf", O_RDONLY)        = 4
open("/etc/hosts", O_RDONLY)            = 4
open("/etc/ld.so.cache", O_RDONLY)      = 4
open("/lib/tls/libnss_dns.so.2", O_RDONLY) = 4
open("/etc/hosts", O_RDONLY)            = 4

IPアドレスを書いたとき

# strace ping -c 1 208.77.188.166 2>&1 | grep open
open("/etc/ld.so.preload", O_RDONLY)    = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY)      = 3
open("/lib/tls/libresolv.so.2", O_RDONLY) = 3
open("/lib/tls/libc.so.6", O_RDONLY)    = 3