“A” record(address record) - returns a 32-bit IPv4 address, most commonly used to map hostnames to an IP address of the host.
“MX” record(mail exchange record) - maps a domain name to a list of mail exchange servers for that domain.
“CNAME” record(canonical name record) - is an alias of one name to another, the DNS lookup will continue by retrying the lookup with the new name. This is useful when running multiple services (like an FTP and a webserver) from a single IP address. Each service can then have its own …

Currently 1 of the server under my monitoring is down. I check it and found that the httpd service cannot be started.
When i try to restart the service, it give me the following error:
(98)Address already in use: make_sock: could not bind to address 0.0.0.0:80
no listening sockets available, shutting down
Unable to open logs
I ran this command in terminal:
[root@inertz home]#lsof -i :80
COMMAND PID USER FD TYPE DEVICE SIZE NODE NAME
shbd 8050 nobody 6u IPv4 …