2. RPM 패키지 업데이트 버전 확인

#rpm -qa | grep glibc
glibc-devel-2.5-123.el5_11.1
compat-glibc-headers-2.3.4-2.26
compat-glibc-2.3.4-2.26
compat-glibc-2.3.4-2.26
glibc-common-2.5-123.el5_11.1
glibc-devel-2.5-123.el5_11.1
glibc-2.5-123.el5_11.1
glibc-2.5-123.el5_11.1
glibc-headers-2.5-123.el5_11.1

3. RPM 명령어를 이용하여 패키지 다운그레이드 하기

1). 기존 패키지 확인 및 백업
# rpm -qa | grep glibc
glibc-devel-2.5-81
compat-glibc-headers-2.3.4-2.26
compat-glibc-2.3.4-2.26
compat-glibc-2.3.4-2.26
glibc-2.5-81
glibc-2.5-81
glibc-headers-2.5-81
glibc-devel-2.5-81

2). 다운그레이드를 위한 기존 패키지 목록
glibc-2.5-81.x86_64.rpm
glibc-common-2.5-81.x86_64.rpm
glibc-2.5-81.i686.rpm
nscd-2.5-81.x86_64.rpm
glibc-headers-2.5-81.x86_64.rpm
glibc-devel-2.5-81.x86_64.rpm
glibc-devel-2.5-81.i386.rpm

3). RPM 명령어 중 --force (강제) 명령어를 이용하여 패키지 다운그레이드 시작 
# rpm -Uvh --force glibc-2.5-81.x86_64.rpm glibc-common-2.5-81.x86_64.rpm glibc-2.5-81.i686.rpm nscd-2.5-81.x86_64.rpm glibc-headers-2.5-81.x86_64.rpm glibc-devel-2.5-81.x86_64.rpm glibc-devel-2.5-81.i386.rpm
warning: glibc-2.5-81.x86_64.rpm: Header V3 DSA signature: NOKEY, key ID 37017186
Preparing...                ########################################### [100%]
   1:glibc-common           ########################################### [ 14%]
   2:glibc                  ########################################### [ 29%]
   3:glibc-headers          ########################################### [ 43%]
   4:nscd                   ########################################### [ 57%]
   5:glibc-devel            ########################################### [ 71%]
   6:glibc                  ########################################### [ 86%]
   7:glibc-devel            ########################################### [100%]

4. 다운그레이드 패키지 버전 확인

# rpm -qa | grep glibc
glibc-devel-2.5-81
compat-glibc-headers-2.3.4-2.26
compat-glibc-2.3.4-2.26
compat-glibc-2.3.4-2.26
glibc-2.5-81
glibc-2.5-81
glibc-headers-2.5-81
glibc-devel-2.5-81
glibc-common-2.5-81