Hi, I have a project that is a library that links against libresolv, It works fine on recent distros: Ubuntu 10.x Fedora 13, Mandriva 2010.1 but on Centos 5.x I get the following errors glibc installed is: glibc-2.5-18.el5_1.1 g++ -DHAVE_CONFIG_H -I. -I./include -I/usr/include/postgresql -O3 -ansi -Wall -Wno-deprecated -D_FORTIFY_SOURCE=0 -MT testUpLog.o -MD -MP -MF .deps/testUpLog.Tpo -c -o testUpLog.o testUpLog.cc mv -f .deps/testUpLog.Tpo .deps/testUpLog.Po /bin/sh ./libtool --tag=CXX --mode=link g++ -O3 -ansi -Wall -Wno-deprecated -D_FORTIFY_SOURCE=0 -L/usr/lib64 -L/lib64 -L/usr/lib64/mysql -o testUpLog testUpLog.o libUpTools.la -lpq -lmysqlclient -lssl -lpthread libtool: link: g++ -O3 -ansi -Wall -Wno-deprecated -D_FORTIFY_SOURCE=0 -o .libs/testUpLog testUpLog.o -L/usr/lib64 -L/lib64 -L/usr/lib64/mysql ./.libs/libUpTools.so -lpq -lmysqlclient -lssl -lpthread ./.libs/libUpTools.so: undefined reference to `__ns_name_uncompress' ./.libs/libUpTools.so: undefined reference to `__ns_initparse' ./.libs/libUpTools.so: undefined reference to `__ns_parserr' collect2: ld returned 1 exit status make[1]: *** [testUpLog] Error 1 make[1]: Leaving directory `/tmp/UpTools-8.5.3' make: *** [check-am] Error 2 library.la file contains: dlname='libUpTools.so.0' library_names='libUpTools.so.0.0.0 libUpTools.so.0 libUpTools.so' old_library='libUpTools.a' inherited_linker_flags='' dependency_libs=' -L/usr/lib64 -L/lib64 -L/usr/lib64/mysql -lpq -lmysqlclient -lssl -lpthread' weak_library_names='' current=0 age=0 revision=0 installed=no shouldnotlink=no dlopen='' dlpreopen='' libdir='/usr/lib' You can read my files on pastebin.com *configure.ac http://pastebin.com/hs5q21Rq *Makefile.am; http://pastebin.com/KW1sGZve Thanks in advance -- -- Sergio Belkin http://www.sergiobelkin.com Watch More TV http://sebelk.blogspot.com Sergio Belkin -