Trouble shooting the apache2 installation in ubuntu 13.04

As usual without any buzz in ubuntu I used the typical command without any issues.

apt-get install apache2

Next I tried to start the installed apache2. 

  apachectl start

But it responded with an error message, saying

AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1. Set the 'ServerName' directive globally to suppress this message
(98)Address already in use: AH00072: make_sock: could not bind to address [::]:80
(98)Address already in use: AH00072: make_sock: could not bind to address 0.0.0.0:80

So by default apache2 server runs on port 80. I used the netstat command to kill the process, responsible to that port. But it kept me giving this result

netstat -ltnp | grep :80 

tcp6 0 0 :::80 :::* LISTEN 15237/apache2
tcp6 0 0 :::8080 :::* LISTEN 10470/java
tcp6 0 0 127.0.0.1:8005 :::* LISTEN 10470/java
tcp6 0 0 :::8009 :::* LISTEN 10470/java

Later I realized, In all cases Killing the process may not work, as the process using the port 80 will get restarted and doesn't allow to use the port. So what can be done is to change the port for apache, if that doesn't matter.

Therefore as a solution for that, I opened the /etc/apache2/ports.conf and changed the Listen port to 8081.

Now, again I tried to start the server and it complained to me as 

" AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1. Set the 'ServerName' directive globally to suppress this message "

So i added a new line "ServerName localhost" in the file /etc/apache2/httpd.conf.

Now the server started without much trouble.