On Sun, 1 Jan 2017 14:11:27 -0800 Rick Moen <r...@linuxmafia.com> wrote:
> Quoting Simon Hobson (li...@thehobsons.co.uk): > > > What do /etc/resolv.conf and /etc/nssswitch.conf have in them ? > > Though to be honest, other than the systems I have BIND running on, > > DNS resolution is something of a black box to me. > > On Linux systems, there is a DNS 'stub resolver' librery 'libresolv' > included in the glibc package, that furnishes the system's > res_query(), res_search(), res_mkquery(), res_send(), res_init(), > dn_comp(), dn_expand() functions, plus higher-level functions such as > gethostbyname() and gethostbyaddr(). See: > https://linux.die.net/man/3/resolver > > This is distressingly ancient and crufty code, going all the way back > to 1980s BSD UNIX. After that, it was inside BIND4, BIND8, and all > BIND9 versions until 9.6.0 as 'libbind'. It was removed from BIND > itself starting BIND 9.6.0. glibc borrowed as 'libresolv' the > version of this code during the long BIND8 era, and kept in sync with > the BIND8 module through BIND 8.2.3-T5B in July 2000, from which > point it has continued to evolve independently in glibc. > > The purpose of a 'stub resolver' is to originate outgoing DNS queries > to a separate _real_ recursive nameserver[1] on- or off-system (e.g., > Unbound, BIND9's recursive functions, MaraDNS, PowerDNS Recursor, > dnscache, Deadwood). > > libresolv is used as a generic glibc interface to all DNS name > resolution methods - from using /etc/hosts file to DNS/NIS/LDAP > services, and system its behaviour is controlled > by /etc/nsswitch.conf and /etc/resolv.conf. > > It should be noted that many programs presume to cache DNS, e.g., Web > browsers do, as does the Java runtime. Also, some systems such as > ones on NIS or LDAP and NFS tend to run dedicated system caching > daemons like GNU's nscd[2] for performance purposes (i.e., to make > performance suck less). > > Possibly of assistance: > http://linuxmafia.com/faq/Network_Other/dns-servers.html > > > [1] Or to a forwarder such as Dnsmasq, DNRD, CurveDNS, dproxy, or > pdnsd, which in turn would need to relay the query to a real > recursive nameserver. > He is probably running dnsmasq (well part of it), is there a line in /etc/hosts that starts '127.0.1.1' ? Rowland _______________________________________________ Dng mailing list Dng@lists.dyne.org https://mailinglists.dyne.org/cgi-bin/mailman/listinfo/dng
