ESXi Hostname Management Guide

Overview

This guide covers changing ESXi hostnames and updating related configurations to maintain consistency across your homelab infrastructure.

Current vs. Target Configuration

Host IP	Current Hostname	Target Hostname	Target FQDN
192.168.10.8	nuc1	esxi-nuc-01	esxi-nuc-01.lab.local
192.168.10.9	nuc2	esxi-nuc-02	esxi-nuc-02.lab.local
192.168.10.10	nuc3	esxi-nuc-03	esxi-nuc-03.lab.local

Domain vs. Hostname vs. FQDN

Understanding the Components

Hostname: Short name identifying the host

Example: esxi-nuc-01
Used for local identification

Domain Name: Network domain the host belongs to

Example: lab.local
Used for DNS hierarchy

FQDN (Fully Qualified Domain Name): Complete DNS name

Example: esxi-nuc-01.lab.local
Used for network services and certificates

Why Update Hostnames?

Benefits of Descriptive Hostnames

Consistency: Matches naming convention used in SSH config
Clarity: Immediately identifies the host type and number
Documentation: Easier to reference in procedures and scripts
Monitoring: Better identification in logs and alerts

Naming Convention

esxi-<hardware-type>-<number>

Examples:
- esxi-nuc-01, esxi-nuc-02, esxi-nuc-03
- esxi-ms-a2-01, esxi-ms-a2-02

Configuration Update Process

Step 1: Update Hostnames

Use the provided script to update all hostnames at once:

./scripts/update-esxi-hostnames.sh

This script will:

Connect to each ESXi host via SSH
Update the hostname using esxcli
Verify the changes
Provide next steps

Step 2: Configure Domain Names (Recommended)

Configure proper domain names and FQDNs:

# Use default domain (lab.local)
./scripts/update-esxi-domains.sh

# Or specify custom domain
./scripts/update-esxi-domains.sh homelab.local
./scripts/update-esxi-domains.sh markalston.net

This script will:

Set proper domain name
Configure FQDN
Verify DNS configuration
Provide DNS setup instructions

Manual Method

For individual hosts or manual verification:

# Connect to ESXi host
ssh root@192.168.10.8

# Check current hostname
hostname -s

# Update hostname
esxcli system hostname set --host=esxi-nuc-01

# Verify change
hostname -s

Post-Update Tasks

1. Update SSH Configuration

After changing hostnames, update your SSH config:

./scripts/deploy-esxi-ssh-keys.sh

This will regenerate SSH config entries with the new hostnames.

2. Update DNS Records (If Applicable)

If using internal DNS, update A records:

esxi-nuc-01.lab.local  → 192.168.10.8
esxi-nuc-02.lab.local  → 192.168.10.9
esxi-nuc-03.lab.local  → 192.168.10.10

3. Update vCenter Inventory

If hosts are managed by vCenter:

In vSphere Client:
- Navigate to Hosts and Clusters
- Right-click each host
- Select “Rename”
- Update to match new hostname

Or via PowerCLI:

# Connect to vCenter
Connect-VIServer -Server vcenter.lab.local
   
# Rename hosts
Get-VMHost -Name "nuc1*" | Set-VMHost -Name "esxi-nuc-01"
Get-VMHost -Name "nuc2*" | Set-VMHost -Name "esxi-nuc-02"
Get-VMHost -Name "nuc3*" | Set-VMHost -Name "esxi-nuc-03"

4. Update Documentation

Update any references in:

Network diagrams
Inventory spreadsheets
Backup scripts
Monitoring configurations
Documentation files

5. Update Backup References

The backup scripts should automatically use the new hostnames, but verify:

# Test VIB backup with new hostnames
./scripts/backup-esxi-vibs.sh

# Test config backup with new hostnames
./scripts/backup-esxi-config.sh

Verification

Check Hostname Resolution

# Test SSH connectivity with new hostnames
ssh esxi-nuc-01 "hostname -s"
ssh esxi-nuc-02 "hostname -s"
ssh esxi-nuc-03 "hostname -s"

Verify ESXi Configuration

# Check hostname in ESXi
ssh esxi-nuc-01 "esxcli system hostname get"

Expected output:

Domain Name: 
Fully Qualified Domain Name: esxi-nuc-01
Host Name: esxi-nuc-01

Check Network Services

Verify that network services still work:

Web UI access (https://192.168.10.8)
vCenter connectivity
Storage connections
Backup operations

Troubleshooting

Hostname Not Changed

If hostname doesn’t update immediately:

# Check hostname configuration
esxcli system hostname get

# Restart management services
/etc/init.d/hostd restart
/etc/init.d/vpxa restart

SSH Connection Issues

If SSH stops working after hostname change:

Use IP address to connect
Check SSH service status
Regenerate SSH keys if needed

vCenter Communication Issues

If vCenter loses connectivity:

Reconnect Host:
- In vSphere Client
- Right-click host → Connection → Connect

Update Host Certificates (if required):

# On ESXi host
/sbin/generate-certificates
/etc/init.d/hostd restart

Best Practices

Timing Considerations

Maintenance Window: Change hostnames during scheduled maintenance
VM Impact: No downtime required for VMs
vCenter: May show temporary warnings during change

Pre-Change Checklist

Backup current ESXi configuration
Document current network settings
Notify team of hostname changes
Plan rollback procedure

Rollback Procedure

If issues arise, revert hostnames:

# Example rollback for nuc1
ssh root@192.168.10.8 "esxcli system hostname set --host=nuc1"

Security Considerations

Certificate Implications

Hostname changes may affect:

SSL certificates
vCenter trust relationships
Host profiles

Access Control

Ensure hostname changes don’t affect:

User permissions
Service account access
Backup operations

Future Hostname Changes

Planned Additions

When adding MS-A2 hosts:

esxi-ms-a2-01 (192.168.10.100)
esxi-ms-a2-02 (192.168.10.101)

Maintenance Script

Consider creating a maintenance script for future hostname changes:

#!/bin/bash
# update-single-hostname.sh <ip> <new-hostname>
ssh root@$1 "esxcli system hostname set --host=$2"

Summary

Hostname updates improve infrastructure organization and consistency. The automated script simplifies the process while maintaining proper verification and documentation of changes.

Key benefits:

Improved clarity and documentation
Consistent naming across infrastructure
Better integration with monitoring and automation
Easier troubleshooting and maintenance