Description of problem:

Updating sudo to latest
sudo-1.7.2p1-14.el5_8.2
b0rked server to inability to resolve any local name

ie
/etc/hosts
127.0.0.1  localhost testname

some programs cannot resolve that anymore like php, python scripts
but interestingly ping(8) works.

I resolved this by
yum remove sudo
yum downgrade glibc glibc-common nscd
yum update glibc
yum install sudo

and now local name resolving works.