Permission denied: make_sock: could not bind to address

Could not start apache2 on a specific port ? (running centos or selinux enabled os) ?

Check that the port is authorized :

semanage port -l | grep -w http_port_t

If not you've got to authorize it :

semanage port -a -t http_port_t -p tcp <PORT>

If semanage is not installed :

yum -y install policycoreutils-python

cf. : ici