resolv.conf(5) File Formats Manual resolv.conf(5) (NAME) resolv.conf - (Resolver) (SYNOPSIS) /etc/resolv.conf (DESCRIPTION) (resolver) C (DNS) . . . DNS trust-ad . (hostname) . : nameserver IP IPv4 ( ) IPv6 ( ) RFC 2373. MAXNS ( ) . . nameserver . ( .) search : . gethostname(2) '.' . '.' (root domain) . search (tab) . ndots ( ) . options ndots:n (man-in-the-middle) DNS . (timeout) . search . glibc 2.25 . glibc 2.26 . domain search . sortlist gethostbyname(3) . (sortlist) IP (netmask) . . IP () . . : sortlist 130.155.160.0/255.255.240.0 130.155.0.0 options . : options option ... option : debug RES_DEBUG _res.options ( glibc resolver(3) ). ndots:n res_query(3) ( resolver(3) ) . n . . timeout:n . API API . RES_TIMEOUT ( ). . attempts:n . RES_DFLRETRY ( ). . rotate RES_ROTATE _res.options (round-robin) . . no-aaaa ( glibc 2.36) RES_NOAAAA _res.options AAAA (stub resolver) AAAA NSS getaddrinfo(3) . DNS : IPv6 hosts(5) getaddrinfo(3) AI_PASSIVE IPv6 IPv6 . (NXDOMAIN) AAAA A . DNS AAAA . EDNS0 DNSSEC . no-check-names RES_NOCHECKNAME _res.options BIND (_) (non-ASCII) . inet6 RES_USE_INET6 _res.options . gethostbyname(3) A AAAA AAAA A IPv4 << >> IPv6 . glibc 2.25 gethostbyname(3) getaddrinfo(3) . . ip6-bytestring ( glibc 2.3.4 glibc 2.24) RES_USEBSTRING _res.options . IPv6 (bit-label) RFC 2673 ( ) (nibble) . glibc 2.25 DNS . ip6-dotint/no-ip6-dotint ( glibc 2.3.4 glibc 2.24) RES_NOIP6DOTINT _res.options / . () (ip6-dotint) IPv6 () ip6.int () (no-ip6-dotint) IPv6 ip6.arpa . glibc 2.24 no-ip6-dotint . ip6-dotint glibc 2.25 . edns0 ( glibc 2.6) RES_USE_EDNS0 _res.options . DNS RFC 2671 . single-request ( glibc 2.10) RES_SNGLKUP _res.options . glibc glibc 2.9 IPv4 IPv6 () . DNS / . glibc IPv6 IPv4 ( ). single-request-reopen ( glibc 2.9) RES_SNGLKUPREOP _res.options . A AAAA . . . (port) . no-tld-query ( glibc 2.14) RES_NOTLDQUERY _res.options . res_nsearch() ( ) (TLD) . localhost <> TLD . RES_DEFNAMES RES_DNSRCH . use-vc ( glibc 2.14) RES_USEVC _res.options . TCP DNS . no-reload ( glibc 2.26) RES_NORELOAD _res.options . . trust-ad ( glibc 2.31) RES_TRUSTAD _res.options . AD (stub resolver) . AD DNSSEC . AD DNSSEC (opt-in) . trust-ad AD DNS ( AD) AD . AD . trust-ad AD . glibc 2.30 AD . search resolv.conf LOCALDOMAIN . options resolv.conf RES_OPTIONS ( options ) . ( nameserver) . . (;) (#) () . (FILES) /etc/resolv.conf, (SEE ALSO) gethostbyname(3), resolver(3), host.conf(5), hosts(5), nsswitch.conf(5), hostname(7), named(8) Name Server Operations Guide for BIND 4th Berkeley Distribution 2024-05-02 resolv.conf(5)