When setting up servers, two fundamental naming concepts come into play:

• Hostname: A simple label identifying a device on a network (e.g., myfileserver)
• Fully Qualified Domain Name (FQDN): The complete address that specifies both host and domain hierarchy (e.g., fileserver.company.com)

Local Network Configuration

For internal services like a file server, a hostname alone often suffices:

# Example in /etc/hosts
192.168.1.100  myfileserver

Internet-Accessible Services

Public-facing services require FQDNs for proper DNS resolution:

# Typical DNS record setup
webserver     IN  A      203.0.113.45
mail          IN  CNAME  webserver.company.com.

Consider these configuration examples:

Linux Hostname Setup

# View current hostname
hostnamectl status

# Set hostname temporarily
hostname mydevserver

# Set hostname permanently
hostnamectl set-hostname mydevserver

Web Server Configuration

Apache virtual host example using FQDN:

<VirtualHost *:80>
    ServerName www.example.com
    ServerAlias example.com
    DocumentRoot /var/www/html
    ErrorLog ${APACHE_LOG_DIR}/error.log
    CustomLog ${APACHE_LOG_DIR}/access.log combined
</VirtualHost>

• Using unqualified hostnames in SSL certificates
• Forgetting to update both forward/reverse DNS records
• Mismatched hostname/FQDN in service configurations

Check your configuration with these commands:

# Verify FQDN resolution
hostname -f

# Check DNS records
dig +short example.com

# Test connectivity
ping -c 4 fileserver.localdomain

In network administration, a hostname is the human-readable label assigned to a device on a network. It's the basic identifier that helps users and systems recognize a machine without needing its IP address.

A Fully Qualified Domain Name (FQDN) represents the complete, unambiguous address of a host in the DNS hierarchy. It specifies the exact location of a device within the domain namespace.

# Example hostname: fileserver
# Example FQDN: fileserver.company.local

For a local file server, you typically use a simple hostname:

# In /etc/hostname (Linux) or hostname command (Windows)
myfileserver

For internet-facing services, FQDNs are mandatory:

# Web server FQDN
web01.prod.example.com

# Mail server FQDN
mail.exchange.example.com

Here's how you might configure DNS records for different scenarios:

# Local network DNS zone file example
fileserver IN A 192.168.1.10
; Simple hostname resolution

# Public DNS example
www IN CNAME webserver.prod.example.com.
webserver.prod.example.com. IN A 203.0.113.45

When configuring web servers, the FQDN becomes critical:

# Apache VirtualHost configuration

    ServerName www.example.com
    ServerAlias example.com
    DocumentRoot /var/www/html


# Nginx server block
server {
    listen 80;
    server_name mail.example.com;
    ...
}

Always ensure:

• Hostnames should be unique within their domain
• FQDNs must be resolvable through DNS
• SSL certificates require FQDNs, not simple hostnames

# Testing FQDN resolution
nslookup webserver.prod.example.com
ping -a 192.168.1.10