"Could not reliably determine the server's fully qualified domain name, using xxx.abc.com for ServerName"
Please check on your httpd.conf for the "ServerName" variable, if you have not set it any or it has been commented. Try to uncomment this line as below:
# ServerName gives the name and port that the server uses to identify itself.
# This can often be determined automatically, but we recommend you specify
# it explicitly to prevent problems during startup.
# If your host doesn't have a registered DNS name, enter its IP address here.
#or just simple uncomment this line to use default value
Do a "apachectl -t" again, and your error should disappears.