sed
:
sed -E '
s/^(rhts-mgr hostname +g)[0-9]+(\-rhts.*)$/8/;
s/^(rhts-mgr.* 10\.113\.)[0-9]+(\..*)$/5/;
s/^(rhts-cntrl.* 10\.113\.)[0-9]+(\..*)$/3/
' file
Perl:
perl -ne '
s/^(rhts-mgr hostname\s+g)\d+(\-rhts.*)$/${1}08${2}/;
s/^(rhts-mgr.* 10\.113\.)\d+(\..*)$/${1}55${2}/;
s/^(rhts-cntrl.* 10\.113\.)\d+(\..*)$/${1}53${2}/;
print
' file