resolv.conf question

[javaguy]

I have a question about resolv.conf. Where does it come from?

 

I recently moved my web page from a hosted server to my own machine using ZoneEdit. I had the domain registrar change my name servers appropriately, but after a week I still couldn't see my web page. Then I discovered that everybody else in the world could see it.

 

So I did a dig command and discovered that dig still showed my domain at the old name servers. I went into resolv.conf and found three IP addresses there. I did a dig to the first one and got the old (wrong) name server. I did it with the other two and got the right answer, the ZoneEdit name servers, but I guess if it finds the domain on the first one there's no reason to check the others.

 

So I just deleted the first one from my resolv.conf, since it apparently doesn't update its name server stuff. But an hour later, it was back in there. I deleted it again, and once again I could browse to my web site, but then after a while I couldn't any more, and sure enough the offending server had been added to my resolv.conf again. What gives? And how do I fix it?

 

Thanks!

Sam

[devries]

It's a dhcp problem. The dhcp server refreshes resets the informations in the resolv.conf file.

 

Solution: Turn of the dhcp server

or: make the resov.conf not writable

or: There is a file you can edit but I don't know what file or what to change and I can't find it googling so maybe your better of with the first 2 suggestions :)

 

Good luck

[javaguy]

The DHCP server? I didn't know I was running one. How do I turn it off? I thought the DHCP server was where my computer gets its IP address when I boot up (or restart the network, or whatever), and I need that, don't I?

 

Sorry, I'm still pretty new to Linux configuration, so please bear with me. :)

[Vdubjunkie]

DHCP server is what provides an IP, so what you need to obtain an IP is actually DHCP client which typically shows up in a

ps auxw

as "dhclient"

I'm not certain myself what is causing your problem, but I know that when I've adjusted my /etc/resolv.conf or my /etc/hosts files directly, I've come to the understanding that the OS was actually using $HOME/tmp/hosts or something like that. Maybe do a

find / -name "hosts"

and same for resolv.conf to see where all it shows up. Perhaps that can help some.

[bvc]

[root@localhost root]# slocate resolv.conf

/etc/resolv.conf

/usr/share/man/man5/resolv.conf.5.bz2

[root@localhost root]# man resolv.conf

NAME
    resolver - resolver configuration file

SYNOPSIS
    /etc/resolv.conf

DESCRIPTION
    The resolver is a set of routines in the C library (resolve(3)) that pro-
    vide access to the Internet Domain Name System.  The resolver configura-
    tion file contains information that is read by the resolver routines the
    first time they are invoked by a process.  The file is designed to be
    human readable and contains a list of keywords with values that provide
    various types of resolver information.

    On a normally configured system, this file should not be necessary.  The
    only name server to be queried will be on the local machine, the domain
    name is determined from the host name, and the domain search path is con-
    structed from the domain name.[code]

    The different configuration directives are:

    nameserver
             Internet address (in dot notation) of a name server that the
             resolver should query.  Up to MAXNS (see <resolv.h>) name
             servers may be listed, one per keyword.  If there are multiple
             servers, the resolver library queries them in the order listed.
             If no nameserver entries are present, the default is to use the
             name server on the local machine.  (The algorithm used is to try
             a name server, and if the query times out, try the next, until
             out of name servers, then repeat trying all the name servers
             until a maximum number of retries are made).

    domain   Local domain name.  Most queries for names within this domain
             can use short names relative to the local domain.  If no domain
             entry is present, the domain is determined from the local host
             name returned by gethostname(2); the domain part is taken to be
             everything after the first `.'.  Finally, if the host name does
             not contain a domain part, the root domain is assumed.

    search   Search list for host-name lookup.  The search list is normally
             determined from the local domain name; by default, it contains
             only the local domain name.  This may be changed by listing the
             desired domain search path following the search keyword with
             spaces or tabs separating the names.  Most resolver queries will
             be attempted using each component of the search path in turn
             until a match is found.  Note that this process may be slow and
             will generate a lot of network traffic if the servers for the
             listed domains are not local, and that queries will time out if
             no server is available for one of the domains.

             The search list is currently limited to six domains with a total
             of 256 characters.

    sortlist
             Allows addresses returned by gethostbyname to be sorted.  A
             sortlist is specified by IP address netmask pairs. The netmask
             is optional and defaults to the natural netmask of the net. The
             IP address and optional network pairs are separated by slashes.
             Up to 10 pairs may be specified.  For example:

                   sortlist 130.155.160.0/255.255.240.0 130.155.0.0

    options  Allows certain internal resolver variables to be modified.  The
             syntax is
                   options option ...
             where option is one of the following:

             debug     sets RES_DEBUG in _res.options.

             ndots:n   sets a threshold for the number of dots which must
                       appear in a name given to res_query() (see
                       resolver(3)) before an initial absolute query will be
                       made.  The default for n is ``1'', meaning that if
                       there are any dots in a name, the name will be tried
                       first as an absolute name before any search list ele-
                       ments are appended to it.

             timeout:n
                       sets the amount of time the resolver will wait for a
                       response from a remote name server before retrying the
                       query via a different name server.  Measured in sec-
                       onds, the default is RES_TIMEOUT (see <resolv.h> ).

             attempts:n
                       sets the number of times the resolver will send a
                       query to its name servers before giving up and return-
                       ing an error to the calling application.  The default
                       is RES_DFLRETRY (see <resolv.h> ).

             rotate    sets RES_ROTATE in _res.options, which causes round
                       robin selection of nameservers from among those
                       listed.  This has the effect of spreading the query
                       load among all listed servers, rather than having all
                       clients try the first listed server first every time.

             no-check-names
                       sets RES_NOCHECKNAME in _res.options, which disables
                       the modern BIND checking of incoming host names and
                       mail names for invalid characters such as underscore
                       (_), non-ASCII, or control characters.

             inet6     sets RES_USE_INET6 in _res.options.  This has the
                       effect of trying a AAAA query before an A query inside
                       the gethostbyname function, and of mapping IPv4
                       responses in IPv6 ``tunnelled form'' if no AAAA
                       records are found but an A record set exists.

    The domain and search keywords are mutually exclusive.  If more than one
    instance of these keywords is present, the last instance wins.
    The search keyword of a system's resolv.conf file can be overridden on a
    per-process basis by setting the environment variable ``LOCALDOMAIN'' to
    a space-separated list of search domains.

    The options keyword of a system's resolv.conf file can be amended on a
    per-process basis by setting the environment variable ``RES_OPTIONS to a
    space-separated list of'' resolver options as explained above under
    options.

    The keyword and value must appear on a single line, and the keyword
    (e.g., nameserver) must start the line.  The value follows the keyword,
    separated by white space.

FILES
    /etc/resolv.conf <resolv.h>

SEE ALSO
    gethostbyname(3), hostname(7), named(8), resolver(3), resolver(5).
    ``Name Server Operations Guide for BIND''

4th Berkeley Distribution      November 11, 1993     4th Berkeley Distribution

 

 

interesting

On a normally configured system, this file should not be necessary.  The

    only name server to be queried will be on the local machine, the domain

    name is determined from the host name, and the domain search path is con-

    structed from the domain name

[root@localhost root]# urpmf resolv.conf

mindi:/usr/share/mindi/rootfs/etc/resolv.conf

gscanbus:/etc/guid-resolv.conf

gscanbus:/etc/oui-resolv.conf

howto-sgml-nl:/usr/share/doc/HOWTO/SGML/nl/Casema-kabelmodem-HOWTO-NL/scripts/resolv.conf

ppp:/etc/ppp/resolv.conf

ppp:/var/run/ppp/resolv.conf

naat-backend:/usr/share/naat/events/ADSLProviderDNS1/main/template--etc--resolv.conf

naat-backend:/usr/share/naat/events/ADSLProviderDomain/main/template--etc--resolv.conf

naat-backend:/usr/share/naat/events/DNSPrimaryIP/main/template--etc--resolv.conf

naat-backend:/usr/share/naat/events/DNSSecondaryIP/main/template--etc--resolv.conf

naat-backend:/usr/share/naat/events/DNSServer/main/template--etc--resolv.conf

naat-backend:/usr/share/naat/events/DomainName/main/template--etc--resolv.conf

naat-backend:/usr/share/naat/events/ISDNProviderDomain/main/template--etc--resolv.conf

naat-backend:/usr/share/naat/events/InternetAccessType/main/template--etc--resolv.conf

naat-backend:/usr/share/naat/events/PPPProviderDNS1/main/template--etc--resolv.conf

naat-backend:/usr/share/naat/events/PPPProviderDomain/main/template--etc--resolv.conf

naat-backend:/usr/share/naat/templates/etc/resolv.conf

howto-html-nl:/usr/share/doc/HOWTO/HTML/nl/Casema-kabelmodem-NL/Casema-kabelmodem-HOWTO-NL/scripts/resolv.conf

man-pages:/usr/share/man/man5/resolv.conf.5.bz2

man-pages-de:/usr/share/man/de/man5/resolv.conf.5.bz2

man-pages-es:/usr/share/man/es/man5/resolv.conf.5.bz2

man-pages-fr:/usr/share/man/fr/man5/resolv.conf.5.bz2

man-pages-ja:/usr/share/man/ja/man5/resolv.conf.5.bz2

man-pages-pl:/usr/share/man/pl/man5/resolv.conf.5.bz2

man-pages-pt_BR:/usr/share/man/pt_BR/man5/resolv.conf.5.bz2

man-pages-ru:/usr/share/man/ru/man5/resolv.conf.5.bz2

naat-backend-devel:/usr/src/naat-backend-devel/naat-backend-0.8/templates/etc/resolv.conf

[root@localhost root]#

 

so why do i have one? why have I always had one? what creates and updates it? It's there, and the info updated and correct as always? Needed? lets rename>reboot> and see :P

/my guess? yes, it is needed ;)

Edited September 16, 2004 by bvc

[bvc]

like always....a new one is created.....by dhcp-client (dhclient)

 

SEE:man /usr/share/man/man5/dhclient.conf.5.bz2

man dhclient.conf

for parameters, for the /etc/dhclient.conf file. Should have what you need.

 

In the past I have uninstalled dhcp-client and it complained it couldn't find resolv.conf. I had no internet.

Edited September 16, 2004 by bvc