The Lazy Networker

Tag: network

  • What is Power over Ethernet (PoE)?

    Power over Ethernet (PoE) allows network cables to carry both data and electrical power to devices like IP phones, wireless access points, and security cameras, eliminating the need for separate power adapters.

    PoE Standards

    StandardMax Power per PortDevices Supported
    802.3af (PoE)15.4WPhones, small APs
    802.3at (PoE+)30WHigh-power APs, cameras
    802.3bt (PoE++)60-100WLED lights, laptops

    How to Enable PoE on a Cisco Switch

    Most Cisco switches support PoE by default, but you can manually enable or configure it.

    1. Check if the Switch Supports PoE

    Run:

    Switch#show power inline

    If you see available power and usage stats, the switch supports PoE.

    2. Enable PoE on an Interface

    Run:

    Switch#conf t
    interface <interface_id>
    power inline auto
    exit
    • <interface_id> → Example: GigabitEthernet1/0/1
    • auto → Enables PoE when a powered device (PD) is detected.

    To disable PoE on a port:

    Switch#conf t
    interface <interface_id>
    power inline never
    exit

    3. Set Power Limits for Devices

    By default, the switch assigns power dynamically. You can manually set power limits:

    Switch#conf t
    interface <interface_id>
    power inline static max 20000
    exit
    • Max power in milliwatts (mW)
      • 15000 for 15W (PoE)
      • 30000 for 30W (PoE+)
      • 60000 for 60W (PoE++)

    To check power consumption:

    Switch#show power inline interface <interface_id> detail

    4. Troubleshoot PoE Issues

    If a device is not powering up:

    • Check PoE status:bashCopyEditshow power inline interface <interface_id>
    • Reset PoE on the port:bashCopyEditconf t interface <interface_id> power inline never power inline auto exit
    • If the port is err-disabled, recover it:bashCopyEditconf t interface <interface_id> shutdown no shutdown exit
    • If power is exhausted, check:bashCopyEditshow power inline

    Summary

    TaskCommand
    Enable PoEpower inline auto
    Disable PoEpower inline never
    Set power limitpower inline static max <mW>
    Check PoE statusshow power inline
    Check port power useshow power inline interface <interface_id> detail

  • What is DNS over HTTPS (DoH)

    DNS over HTTPS (DoH) is a protocol that encrypts Domain Name System (DNS) queries and responses between a client (e.g., a web browser or operating system) and a DNS resolver (e.g., Quad9). This encryption protects DNS data from being intercepted, modified, or logged by third-party entities, such as Internet Service Providers (ISPs) or network administrators.

    How does Quad9’s DoH service work?
    Quad9 offers a DoH service that uses the HTTPS protocol to encrypt DNS queries and responses. When you configure your device to use Quad9’s DoH service, your device will send DNS queries to Quad9’s servers over an encrypted HTTPS connection. Quad9’s servers will then respond with the resolved IP addresses, also encrypted.

    How to configure DNS over HTTPS (DoH) using Quad9:
    Android (Android 9 and later):
    Go to Settings > Network & Internet > Advanced > Private DNS.
    Select “Private DNS provider hostname” and enter dns.quad9.net.
    Save the changes.

    iOS (14 and later):
    Note that Apple’s Private Relay feature will override any custom DoH settings. If you want to use Quad9’s DoH, disable Private Relay.
    Configure your device’s DNS settings to use Quad9’s DoH by following these steps:
    Go to Settings > Wi-Fi > [your Wi-Fi network] > DNS.
    Tap “Manual” and enter dns.quad9.net as the DNS server.

    Windows 11:
    Go to Settings > Network & Internet > Ethernet or Wi-Fi > Change adapter options.
    Right-click your active network connection and select “Properties”.
    In the “Internet Protocol Version 4 (TCP/IPv4)” or “Internet Protocol Version 6 (TCP/IPv6)” properties, click “Advanced”.
    In the “DNS” tab, click “Add” and enter dns.quad9.net as the DNS server.

    Other devices and operating systems:
    Consult your device’s documentation or manufacturer’s website for specific instructions on configuring DoH with Quad9.

    Important notes:
    Quad9’s DoH service only blocks malicious domains, not ads or tracking. You may need additional tools to block these types of content.
    If you’re using a VPN, it’s recommended to use the VPN’s built-in DNS service instead of configuring DoH with Quad9.
    Quad9’s DoH service may not work on all networks or devices due to restrictions imposed by network administrators or firewalls.

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