SUMMARY: DNS not working with /etc/hosts

From: Javaid Siddiqi (
Date: Fri Jun 03 1994 - 10:13:29 CDT

Hello Fellow Sun-Managers

First of all I really apologise for not reading the FAQ's very closely. I went
through them once, a couple of weeks ago, but sure overlooked the answer.
I got an over whelming response and I am very grateful to everyone who

Some people got confused with the question. Simply I am using one
sun as the DNS server. All the other machines (SCO, AIX, OS/2, etc ) are using
the Sun's DNS successfully. But the Sun can not resolve hostnames if I remove
sun's /etc/hosts file. The Sun will only look at its own /etc/hosts file.

>From all the responses I got there are two solutions to this as I have it listed
below and mentioned in FAQ's.

        1. Re-build the shared library version of libc .... (see below)
        2. Run NIS with the "hosts" maps only ... (see below)

I am going to setup NIS and use NIS in conjuction with DNS which seems to be an easier solution.

I am having a problem using /etc/hosts in conjunction with DNS. I am running
SunOS 4.1.3 as a Domain Name Server (DNS) using a Sun SparcStation 2. I have
a hetrogeneous environment with DOS, OS/2 and UNIX machines (e.g OS/2
machines using OS/2 TCP/IP, PC's running SCO UNIX, Solaris x86, UnixWare,
PowerPC's running AIX 3.2, IBM RISC 6000's running AIX 3.x). I only keep
bare /etc/hosts file containing entries for the host itself and the loopback
entry on all these machines.

The interesting part is that all these machines EXCEPT the Sun are using Sun's
Domain Name Services without any problems (i.e.resolve names not in their host
table by querying the Sun). Everytime a new machine is installed all I have to
do is to add the /etc/resolv.conf (UNIX machines) and TCPIP\ETC\RESOLV for
(OS/2 machines) to start using DNS.

I have the same /etc/resolv.conf file on the Sun also, but the Sun refuses to
query itself :-( The Sun will only resolv entries from the /etc/hosts file.

What am I missing ... ?? I really would like to use DNS on the Sun everytime
we update our DNS stuff and not have to make changes in two places.


I got similar responses from many people. This is also in section 3 of the FAQ.
I am just going to list it here for your reference. I am going to setup NIS and
use NIS in conjuction with DNS which seems to be an easier solution.

From: Ric Anderson:

 1) How to get DNS working when not running NIS ?

        Note: Solaris2.x users should see question 64..
        The "normal" behavior of a hostname lookup under NIS is to
        consult the NIS hosts map and then DNS (if configured). If
        you are not running NIS the system will only look in
        the /etc/hosts file.

        You have two options to correct this situation:

        A) Re-build the shared library version of libc with replacement
           resolver routines which understand DNS. Resolv+ provides one
           of the best sets of replacement routines and it cames with
           detailed instructions. Also, it will take of fixing the
           many problems with the normal Sun shared library rebuild.
           Finally, resolv+ can be obtained from
           Get the file /pub/sun-faq/resolv+2.1.1.tar.Z.

           Rebuilding the shared library will not allow statically
           linked binaries to do name resolving and these binaries
           will only use /etc/hosts. You can get "dynamically linked"
           replacements for these via anonymous ftp to
  and get the file
           This file only contains sun4 binaries.
           To be able to rebuild shared libraries you need to
           install the "shlib custom" option which is avaiable
           with SunOS version 4.1 or greater.

           If you want to do it under 4.0.3 you need to get the
           patches available from in the
           /systems/sun/sun-fixes directory. You will need the following
                lib.msg, libc_pic.a.sun3 or libc_pic.a.sun4 and

           Make sure to get the README that cames with these files.
           It is in the same directory.
           Note: You can still use NIS for other things in environment,
           such as passwd, and group maps.

        B) Run NIS with the "hosts" maps only. If you
           only need DNS capability than change the "all"
           line /var/yp/Makefile to "all: hosts".

           It does not require any changes to shared libraries.
           See question 2 for complete directoins on how to setup
           DNS with NIS.
 2) How to get DNS to be used when running NIS ?

        First setup the appropriate /etc/resolv.conf file.
        Something like this should do the "trick".

        ; Data file for a client.
        domain local domain
        nameserver address of primary domain nameserver
        nameserver address of secondary domain nameserver

        where: "local domain" is the domain part of the hostnames.
                 For example, if your hostname is ""
                 your "local domain" is "".

        You will need to put a copy of this resolv.conf on
        all NIS(YP) servers including slaves.

        Under SunOS 4.1 and greater, change the "B=" at the top
        of the /var/yp/Makefile to "B=-b" and setup NIS in the
        usual fashion.

        You will need reboot or restart ypserv for these changes
        to take affect.

For Method A, ( Thanks to John Murray)
                        NEW BIND FOR SUNS 2/11/91

[Partially taken from the document "Making a for DNS without NIS"
 that has been distributed to various SunOS users, and seen on Usenet.

 Original document by Paul Balyoz (
 Updated to include OS4.1.2 information, Hal Pomeranz, 3/3/92.
 Minor revisions by Brian Utterback, 4/4/94.

This document tells how to install a NEW version of the BIND Name Server
resolver routines into the shared C library of a Sparcstation running
SunOS 4.1 through SunOs 4.1.3_u1. The procedure is a bit different when
you are trying to install a version of BIND distributed from Berkeley,
compared to the (older) resolver library that comes with SunOS.

A. Get BIND version 4.8.3 or later. We must fix the Makefile in the
resolver directory to do what our sparcstation needs. The whole idea
here is to compile the C source to .o files with the -pic option,
and not do anything fancy to the .o files before putting them into
the new libresolv.a library. Note that we rename your old libresolv.a
file, so that it can be recovered if the new one doesn't work!

        cd Bind4.8.3/res
        vi Makefile
                Comment out all sets of lines that look something like:
                        -ld -r -x file.o
                        mv a.out file.o
                Add to the "CFLAGS" variable the option
                (so that a global tags entry gets added to each .o file)
                Fix paths and options in Makefile as needed.
        mv /usr/lib/libresolv.a /usr/lib/libresolv.a.orig
        make install

This should have created the new /usr/lib/libresolv.a library.

Please also note that the string(3) man-page which comes with SunOS
is more complete than the one distributed with BIND! Therefore you
should NOT replace it as instructed to by BIND's README instructions.

B. Follow the steps below to make a new shared library on your Sun
which includes the new resolver library routines in it.

    1. Become super user by logging in as root, or first as a normal
        user and then typing:

    2. Move into the shared-lib area and make a temporary directory:
                cd /usr/lib/shlib.etc
                mkdir tmp

    3. Move into this new directory, extract the pic (position
        independent code) object files from libc_pic.a and remove
        the SYMDEF file. The renaming (mv commands) is done because
        the "ar" command truncates names to 16 characters.
                cd tmp
                ar x ../libc_pic.a
                rm __.SYMDEF
                mv rpc_dtablesize. rpc_dtablesize.o
                mv rpc_commondata. rpc_commondata.o
                mv xccs.multibyte. xccs.multibyte.o

    4. We now need to extract the object files from your new libresolv.a
        library, making sure not to overwrite two of the Sun objects
        already in this directory:
                mv mktemp.o mktemp.o2 # else it gets stomped
                mv strpbrk.o strpbrk.o2 # else it gets stomped
                ar x /usr/lib/libresolv.a
                mv strpbrk.o2 strpbrk.o # we gotta use Sun's.
                mv mktemp.o2 mktemp.o # we gotta use Sun's.
        (Any other object files that get overwritten are ok.)

        [ Alternatively you can extract Sun's original mktemp.o
          and strpbrk.o files again at this point by typing:
                ar x ../libc_pic.a mktemp.o strpbrk.o ]

    5. Make sure the old host resolver is not still lying around:
                rm gethostent.o
        (ignore error "rm: gethostent.o nonexistent" if you see it.)

    6. Remove the new resolver's string code because Sun's libraries
        already includes this, so it would be redundant:
                rm strcasecmp.o

    7. Go back up to the shared library building directory and
        duplicate the list of object files to use:
                cd ..
                cp lorder-sparc lorder-sparc.orig
    8. Edit this object file list and make the following modifications
        if they haven't already been done before to this file:
                remove: gethostent.o
                add: gethostnamadr.o
        (the last two are new, which Sun's resolver doesn't use)
        After deleting gethostent.o, you can use the following
        patch, or make the changes by hand (in this order):

                *** 149,154 ****
                --- 149,164 ----
                + gethostnamadr.o
                + herror.o
                + sethostent.o
                + res_query.o
                + res_mkquery.o
                + res_send.o
                + res_debug.o
                + res_comp.o
                + res_init.o
                + strerror.o

    9. The Makefile in shlib.etc for building shared libraries
        has one problem when you run it as the super user, since most
        people do not put "." into root's path. So edit the Makefile
        and modify the definition of "OBJSORT" to read:


        If you are using SunOS 4.1.2 or later, change the lines
        (there are two) in the Makefile which read:

                ld -assert pure-text `${OBJSORT} lorder-sparc tmp`

        to read

                ld -assert pure-text `${OBJSORT} lorder-sparc tmp` -ldl

   10. Now we can finally build the shared library. Type:

        What kind of errors might you get? Here's a couple:
        a. It blows up on one of the .o files in tmp, saying
           that the object file is in an inconsistent state.
           SOLUTION: start over; you did something wrong when you
           compiled the new libresolv.a in section A, above.
           Make SURE not to let Makefile "ld" the object files!
        b. It lists hundreds of error lines about offsets or
           addresses being wrong in all your resolver .o files.
           SOLUTION: start over; you needed to specify "-pic"
           to the C compiler when building the libresolv.a library.

   11. If all goes well, you now have a "" in this
        directory. Test it out before installing it systemwide!
        You can do this by pointing your shell's library path
        variable to the current directory, then trying various
        networking commands:
                setenv LD_LIBRARY_PATH `pwd`
                unsetenv LD_LIBRARY_PATH
        If anything in the library fails, you need to start
        section B over again. Maybe you forgot to use Sun's
        versions of mktemp.o and strpbrk.o; things just won't
        work with BIND's new versions of these files.

   12. When you are sure it's working OK, you can install it
        into the system library directory:
                cp /usr/lib
                chmod 755 /usr/lib/

   13. You can prove that you're using the new library now,
        by watching the output of something like:
                trace date

        The lastest BIND resolver is now installed on your system.
        You can go ahead and compile and install the other BIND
        tools such as named, nslookup, etc. You do not need to
        specify the "-lresolv" library when compiling these tools.

Many thanks to: (Tim Evans) (Pawel Marczewski) (Bradley S. Piatek)
penthesilea.Uni-Trier.DE (Jochen Bern) (Xavier Salvador) (Han Tunca) (Andy Kumeda)
bobr@houston.wireline.SLB.COM (Bob Reardon ) (Ralph Wolman)
ric@Artisoft.COM (Ric Anderson) (Claude Marinier)
crane@cadlab.ECE.Drexel.EDU (Richard Crane) (Nyles Harris)
crane@cadlab.ECE.Drexel.EDU (Richard Crane) (Kevin P. InSCOe) (John Murray)

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