Detecting Multiple DHCP Servers on Your Network

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Yesterday, we introduced a beginner's guide to DHCP. Today, we continue the discussion with:

The Chaos of Multiple DHCP Servers

Imagine this: You’re trying to connect to your network, but your device keeps dropping the connection or displaying an IP conflict error. The culprit might be the existence of multiple DHCP servers on your network.

A DHCP server dynamically assigns IP addresses to devices on a network. When there are two or more DHCP servers present without proper coordination, chaos ensues:

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• IP Address Conflicts: Multiple servers may assign the same IP address to different devices, causing network interruptions.

• Inconsistent Configurations: Each DHCP server may offer different gateway addresses, DNS servers, or subnet masks, leading to connectivity issues.
• Security Risks: An unauthorized DHCP server (also known as a rogue server) can intercept traffic, conduct man-in-the-middle attacks, or disrupt services.

Many smart devices, such as IoT devices, often come with built-in DHCP server capabilities. When connected to a network, these devices can inadvertently act as rogue DHCP servers if not properly configured, leading to network instability. Always check and disable unnecessary DHCP features on IoT devices to maintain network harmony.

To maintain a stable and secure network, it’s crucial to identify and eliminate any rogue DHCP servers. Here’s how you can detect them.

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How to Detect Multiple DHCP Servers on Your Network

1. Using ipconfig /all (Windows)

• Open Command Prompt and run:

  ipconfig /all
  

• This shows the DHCP server currently serving your machine. However, it won’t display multiple servers.

2. Using dhcptest (Windows)

• Download dhcptest from here.
• Run the tool to see responses from all DHCP servers on your network.

3. Using dhcping (Linux/macOS)

• Install and run:

  sudo apt install dhcping  # Debian/Ubuntu
  sudo dhcping -s <broadcast-address>
  

• Multiple responses indicate multiple DHCP servers.

4. Using nmap

• Run this command to discover DHCP servers:

  sudo nmap --script broadcast-dhcp-discover
  

5. Router or Switch Logs

• Check your router’s DHCP lease table or managed switch logs for DHCP server activity.

6. Using Wireshark

• Capture traffic and filter by bootp to see all DHCP offers on the network.

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Preventing DHCP Server Chaos

• Disable unnecessary DHCP servers.
• Use VLANs and DHCP snooping on managed switches.
• Regularly audit your network for unauthorized devices.

Detecting and eliminating rogue DHCP servers ensures your network remains stable, secure, and efficient.

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Understanding DHCP (Dynamic Host Configuration Protocol): A Beginner's Guide

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When you connect to a Wi-Fi network, your device needs an IP address to communicate. Enter DHCP (Dynamic Host Configuration Protocol), the service that automatically hands out IP addresses, making your life easier and more efficient.

What is DHCP?

Think of DHCP like a host at a party handing out name tags. When your device connects to a network, it requests an IP address. The DHCP server offers one, and your device accepts it, ensuring no two devices have the same address. This process is called a DHCP lease, and it's renewed periodically to keep the connection stable.

Why Use DHCP?

Without DHCP, every device would need manual configuration, which is time-consuming and prone to human error. DHCP ensures:

• Automatic IP assignment for new and existing devices
• Avoidance of IP conflicts that disrupt network connectivity
• Seamless connectivity when devices join or leave the network
• Centralized management of network settings, making administration easier

What If There Are Two DHCP Servers?

Two DHCP servers on the same network can cause conflicts, like two hosts handing out name tags from the same list. This can lead to IP conflicts and inconsistent settings. To avoid this:

• Use a single DHCP server for small networks
• Split the IP range between servers in larger networks
• Implement DHCP failover for reliability and redundancy, ensuring uninterrupted service during server outages

Benefits of DHCP

DHCP offers flexibility and scalability, especially in growing networks. It supports mobile devices, remote work, and IoT (Internet of Things) devices that frequently connect and disconnect. By automating IP management, DHCP reduces administrative workload and ensures a more stable network.

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— Dr. Tree (@lannyland.com) January 21, 2025 at 12:29 PM

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Tech Bits: IPv4 vs IPv6

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What is an IP Address?

An IP address (Internet Protocol address) is a unique numerical label assigned to each device connected to a network. It serves two main functions:

1. Identification – It uniquely identifies a device on a network.
2. Location Addressing – It helps route data between devices over the internet.

Every device that connects to the internet, from smartphones to servers, requires an IP address to communicate. The two main types of IP addresses in use today are IPv4 (Internet Protocol version 4) and IPv6 (Internet Protocol version 6).

IPv4 vs. IPv6: Key Differences

IPv4 has been the backbone of internet communications for decades, but with the explosion of internet-connected devices, IPv6 was developed to accommodate the growing demand. Can you believe that IPv6 is also 20+ years old?

Feature	IPv4	IPv6
Address Length	32-bit	128-bit
Address Format	Dotted decimal (e.g., 192.168.1.1)	Hexadecimal colon-separated (e.g., 2001:db8::1)
Number of Addresses	~4.3 billion	~340 undecillion (virtually unlimited)
Header Complexity	More complex	Simplified for efficiency
Security	Optional (IPsec available)	Built-in IPsec support
NAT (Network Address Translation)	Commonly used due to address exhaustion	Not needed due to a larger address space
Auto-Configuration	Uses DHCP	Supports stateless autoconfiguration (SLAAC)

The main reason for transitioning to IPv6 is the exhaustion of IPv4 addresses, which limits the number of devices that can be connected directly to the internet.

How to Ping an IPv4 or IPv6 Address

Pinging an IP address is a useful way to check if a device is reachable on the network.

For IPv4:

On Windows/Linux/macOS, use:

ping 192.168.1.1

For IPv6:

On Windows:

ping -6 2001:db8::1

On Linux/macOS:

ping6 2001:db8::1

If you're using a link-local IPv6 address (starting with fe80::), you must specify the network interface:

ping6 fe80::1%eth0

Replace eth0 with your actual interface name (e.g., wlan0 for Wi-Fi).

Using an IP Address in a Browser Address Bar

You can directly enter an IP address into a web browser’s address bar to access a website or a device’s web interface.

For IPv4:

http://192.168.1.1/

This is common for accessing router configuration pages.

For IPv6:

IPv6 addresses must be enclosed in square brackets:

http://[2001:db8::1]/

If a specific port is required:

http://[2001:db8::1]:8080/

Challenges in Mixed IPv4 and IPv6 Networks

Many local area networks (LANs) operate in a dual-stack environment, meaning they support both IPv4 and IPv6. However, this can introduce some challenges:

1. Compatibility Issues – Some older devices and software do not support IPv6, requiring a fallback to IPv4.
2. Routing Complexity – Managing both IPv4 and IPv6 traffic can require additional network configuration.
3. DNS Resolution Conflicts – Devices may receive both an IPv4 and IPv6 response when resolving a hostname, and network behavior can be unpredictable. <-- This is the biggest risk you want to watch out for!
4. Security Considerations – IPv6’s built-in security features (e.g., IPsec) might not be implemented correctly, leading to potential vulnerabilities.

What Happens if IPv6 is Disabled on the Router?

If IPv6 is disabled on a router, devices in the network will only use IPv4 for communication. This can limit connectivity to IPv6-only services and may cause compatibility issues in mixed networks. Enabling dual-stack is recommended for full compatibility. However, for a home network where you have a limited number of networking devices, this might be a good thing!

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— Dr. Tree (@lannyland.com) January 18, 2025 at 10:40 PM

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Tech Bits: Diving into DNS Records

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Yesterday I explained what DNS is. Today, let's dive deeper into DNS Records.

DNS (Domain Name System) records are the instructions that tell the internet how to route traffic for a domain. These records are stored in DNS servers and play a crucial role in connecting users to websites, email servers, and other online services.

Common Types of DNS Records

1. A Record (Address Record) – Maps a domain to an IPv4 address (e.g., example.com → 192.168.1.1).

2. AAAA Record (IPv6 Address Record) – Similar to an A record but maps to an IPv6 address.

3. CNAME Record (Canonical Name Record) – Creates an alias for a domain, redirecting it to another domain (e.g., www.lannyland.com → lannyland.com).

4. MX Record (Mail Exchange Record) – Directs email to the correct mail server for a domain. (This is how I can receive emails at lannyland.com.)

5. TXT Record (Text Record) – Stores arbitrary text data, often used for verification and security purposes.

6. NS Record (Name Server Record) – Specifies which name servers are authoritative for a domain.

7. SRV Record (Service Record) – Defines the location of services like VoIP or messaging protocols.

8. PTR Record (Pointer Record) – Used for reverse DNS lookups, mapping an IP address to a domain name.

9. SOA Record (Start of Authority Record) – Provides administrative information about a domain, including the primary name server and contact details.

Emails getting routed by DNS MX records

How DNS Records Work

When a user enters a website URL, the DNS resolver queries various DNS records to retrieve the necessary information to load the website or route an email. Each record type serves a specific function and helps ensure smooth communication across the internet.

Why DNS Records Matter

• Website Accessibility – Ensures domains point to the correct web servers.

• Email Routing – Directs email traffic efficiently and securely.

• Security – Helps prevent spoofing and phishing attacks through verification records.

• Load Balancing – Distributes traffic across multiple servers for better performance.

Understanding and correctly configuring DNS records is essential for maintaining a stable and secure online presence. Whether managing a personal website or a large-scale online service, knowing how DNS records function can help troubleshoot issues and optimize performance.

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— Dr. Tree (@lannyland.com) January 13, 2025 at 10:05 PM

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Tech Bits: Understanding DNS, The Internet's Phonebook

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DNS (Domain Name System) is the internet’s phonebook, translating human-friendly website names like www.lannyland.com into numerical IP addresses that computers use to locate and communicate with one another. Without DNS, users would need to remember long, complex IP addresses just to visit their favorite websites, making internet navigation far less intuitive and user-friendly.

How DNS Works

When you type a website address into your browser, a sequence of steps takes place to retrieve the correct IP address:

1. Cache Check – Your browser first looks for a previously stored IP address for the domain to speed up access.
2. Recursive Resolver Inquiry – If the address isn’t found in the cache, your device queries a recursive resolver, usually provided by your Internet Service Provider (ISP).
3. Root Server Lookup – If needed, the resolver asks one of the root DNS servers, which point it in the right direction based on the domain structure.
4. TLD Server Query – The Top-Level Domain (TLD) server (e.g., for .com, .org, .net) helps further refine the search by directing it toward the correct authoritative server.
5. Authoritative Server Response – The website’s authoritative DNS server provides the exact IP address.
6. Website Loading – Your browser now connects to the retrieved IP address, allowing the website to load.

Why DNS Matters

• Public DNS Services – Some users opt for faster and more secure DNS servers like Google’s 8.8.8.8 or Cloudflare’s 1.1.1.1 for better performance and reliability.
• Ease of Use – Users don’t need to memorize long numerical addresses, making the internet more accessible.
• Security Enhancements – DNS filtering can block malicious sites, protecting users from phishing scams and cyber threats.
• Performance Boost – Efficient DNS services can reduce page load times and improve overall browsing speed.

Common DNS Issues and Challenges

• Slow Response Times – Poorly configured or overloaded DNS servers can cause delays in website loading.
• Cache Poisoning (DNS Spoofing) – Hackers can manipulate DNS records to redirect users to fraudulent websites.
• Downtime and Outages – If a major DNS provider experiences an outage, large parts of the internet can become temporarily inaccessible.
• Incorrect Configurations – Improperly configured DNS settings can result in connectivity issues or failure to resolve domain names correctly.

Hosting Multiple Websites on a Single IP

Using Virtual Hosting, multiple domains can share the same IP address. This technique is common in shared hosting environments, where web servers distinguish between different websites using the HTTP Host Header, ensuring that each request reaches the correct site. This allows efficient resource use while accommodating many domains on a single server.

DNS Propagation and Update Delays

Whenever DNS entries are updated, such as changing a domain’s IP address, the changes do not take effect immediately. Instead, they must propagate across various DNS servers worldwide. This process can take anywhere from a few minutes to 48 hours, depending on the Time-To-Live (TTL) settings and cache refresh rates of different DNS providers. During this time, some users may see the updated records, while others may still be directed to the old IP.

Final Thoughts

DNS plays a fundamental role in making internet navigation seamless. Understanding how it works helps users troubleshoot connectivity issues, improve security, and enhance browsing performance. The next time you visit a website, remember that DNS is working behind the scenes to make the connection happen efficiently and securely.

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— Dr. Tree (@lannyland.com) January 10, 2025 at 3:18 PM

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Tech Bits: Google Cloud Run vs Google Cloud Functions

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Google Cloud Run and Google Cloud Functions are both serverless computing solutions offered by Google Cloud Platform (GCP). However, they are very different animals.

Google Cloud Run

A serverless platform for deploying and running containerized applications. Using Docker containers, it offers flexibility to run apps in any language or framework.

Key Features:

• Runs Docker-packaged apps.

• Stateless HTTP workloads.

• Auto-scales traffic, including to zero.

• Supports any containerized language.

• Pay for used CPU, memory, and requests.

Use Cases:

• APIs or microservices.

• Hosting web apps.

• Batch jobs and custom tasks.

• Specialized runtime workloads.

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Google Cloud Functions

A lightweight serverless platform for running single-purpose, event-driven tasks. Developers can focus on code while Google handles infrastructure.

Key Features:

• Triggered by events (e.g., Cloud Storage, Pub/Sub).

• Write small functions in supported languages (Node.js, Python, etc.).

• Auto-scales with event volume.

• Pay for execution time and memory.

Use Cases:

• Event-driven tasks.

• Handling HTTP requests or APIs.

• File processing (e.g., image resizing).

• Pub/Sub message processing.

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Key Differences Between Cloud Run and Cloud Functions

Feature	Google Cloud Run	Google Cloud Functions
Deployment	Containerized apps (Docker).	Single-purpose functions.
Runtime Flexibility	Any containerized language.	Limited runtimes (Node.js, etc.).
Triggers	Stateless HTTP requests.	Events or HTTP triggers.
Scaling	Scales with traffic.	Scales with events.
Complexity	Complex apps or microservices.	Simple, event-based tasks.
Customization	Full control via containers.	Minimal customization.

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Choosing the Right Solution

1. Use Google Cloud Functions if:

   • Workloads are event-triggered (e.g., file uploads).

   • Simplicity and fast setup are priorities.

   • Minimal runtime customization is needed.

2. Use Google Cloud Run if:

   • Building REST APIs, web services, or complex apps.

   • Custom runtime environments or dependencies are required.

   • Consistency between dev and production environments matters.

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Example Scenarios

• Event-Driven Task: Auto-resize images on file upload.

  • Best Option: Cloud Functions

• REST API: Manage inventory with a custom framework.

  • Best Option: Cloud Run

• Background Processing: Process millions of Pub/Sub messages.

• Best Option: Functions for simple logic; Run for complex tasks.

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Tech Bits: GitFlow vs GitLab Flow

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Last time, we discussed Gitflow, Git Feature Branch, and Trunk-Based Development, which are all part of the Git version control system. 

Today, we compare two commonly used workflows, GitFlow and GitLab Flow, which cater to different needs and approaches. This article breaks down their features, strengths, and weaknesses to help you make an informed decision.

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GitFlow: Structured and Ideal for Scheduled Releases

GitFlow, created by Vincent Driessen, is a robust branching model perfect for projects with clearly defined release cycles. It provides a highly organized structure for managing features, releases, and hotfixes.

Key Features:

• Branches:
  • main: Holds production-ready code.
  • develop: Tracks stable development progress.
  • Supporting branches: Feature, release, and hotfix branches for specific tasks.
• Workflow:
  1. Developers create feature branches from develop for new features.
  2. Completed features are merged back into develop.
  3. Release branches are created for finalizing and testing releases before merging into both main and develop.
  4. Hotfix branches are used to address urgent issues in main and are merged back into both main and develop.

Pros and Cons:

• Pros:
  • Provides clear separation of development stages.
  • Ideal for projects with predictable release schedules.
• Cons:
  • High complexity can slow down teams.
  • Less suitable for environments requiring frequent or continuous updates.

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GitLab Flow: Simplicity for Continuous Delivery

GitLab Flow is a modern, streamlined approach optimized for continuous integration (CI) and continuous delivery (CD). It emphasizes simplicity and deployment readiness, making it popular for teams adopting DevOps practices.

Key Features:

• Branches:
  • Minimal branching, with most work happening on main or short-lived feature branches.
  • Optional environment-specific branches (e.g., staging, production) for deployment workflows.
• Workflow:
  1. Developers create feature branches and submit merge requests for peer review and automated testing.
  2. Approved changes are merged directly into main.
  3. CI/CD pipelines automate testing, integration, and deployment.

Pros and Cons:

• Pros:
  • Simplifies branching and deployment processes.
  • Encourages rapid iteration and frequent updates.
• Cons:
  • Lacks structure for managing long-term parallel development.
  • Relies heavily on robust CI/CD systems for success.

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Quick Comparison: GitFlow vs GitLab Flow

Aspect	GitFlow	GitLab Flow
Branching Model	Multi-branch (develop, feature, release, hotfix)	Minimal branching (main, optional environment branches)
Complexity	High	Low
Focus	Release management	Continuous delivery
Use Case	Scheduled releases, complex projects	Frequent updates, DevOps practices

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Choosing the Right Workflow

• Choose GitFlow if your project has clearly defined release cycles, involves long-term maintenance, or requires structured parallel workstreams.
• Choose GitLab Flow if your team operates in a fast-paced environment with frequent deployments and leverages CI/CD pipelines for efficiency.

Here's a great article discussing GitLab Flow in-depth.

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— Dr. Tree (@lannyland.com) January 4, 2025 at 1:08 PM

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Tech Bits: Gitflow, Git Feature Branch, and Trunk-Based Development

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Starting a new blog series (tag) where I'll be sharing bits of tech knowledge from time to time. Through this exercise, I aim to clarify concepts for myself while providing readers with a straightforward way to brush up on their tech knowledge. If you find this series helpful, make sure to click "Tech Bits" in the sidebar to explore more posts.

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Git is an industry-standard tool for managing version control, especially in distributed development environments. How you manage branches in Git can have a major impact on your workflow efficiency. Among the most widely adopted Git workflows are Gitflow Workflow, Git Feature Branch Workflow, and Trunk-Based Development. Each offers unique advantages and is suited to different team dynamics and project requirements. In this post, we’ll break down these workflows and highlight their differences to help you decide which one aligns best with your team's needs.

Gitflow Workflow: Structured and Release-Oriented

Gitflow Workflow is a branching model designed for projects that follow a scheduled release process. Its structure makes it well-suited for teams managing multiple versions or releases of a product.

How It Works:

1. Two primary branches:
   • main (or master): Stores production-ready code.
   • develop: Tracks stable development code.
2. Supporting branches include:
   • Feature branches: Created off develop for new features.
   • Release branches: For preparing a release from develop.
   • Hotfix branches: For urgent fixes applied to main.
3. Features are merged into develop. Releases are merged into both main and develop.

Pros:

• Clear structure with designated branches for different purposes.
• Easy to maintain multiple production versions.
• Great for projects with predictable, periodic releases.

Cons:

• Can become overly complex for small teams or continuous delivery setups.
• Requires careful coordination to avoid bottlenecks.

Git Feature Branch Workflow: Simplicity and Focus

The Git Feature Branch Workflow emphasizes simplicity. Each feature or bug fix is isolated in its own branch, and changes are merged back into the main branch upon completion.

How It Works:

1. Developers create feature branches off the main branch.
2. Once a feature is completed and reviewed, it’s merged back into main.
3. Continuous Integration (CI) pipelines ensure the quality of each change before merging.

Pros:

• Simple and easy to understand.
• Encourages isolated and focused work on specific features or fixes.
• Works well with CI/CD pipelines for automated testing and deployment.

Cons:

• No explicit support for managing releases or parallel versions.
• Larger teams might encounter coordination challenges without additional structure.

Trunk-Based Development: Fast and Continuous

Trunk-Based Development (TBD) is all about speed and frequent integration. Developers work on a single main branch, often referred to as the “trunk.” Any branches created are short-lived, existing only for the time it takes to complete a task.

How It Works:

1. Developers make small, incremental changes and merge them into the main branch quickly.
2. Feature toggles (flags) manage unfinished or experimental code in production.
3. CI/CD pipelines handle testing and deployment to ensure every change is production-ready.

Pros:

• Ideal for fast-paced development and continuous delivery.
• Reduces merge conflicts by encouraging frequent integration.
• Simplifies branch management with minimal branching.

Cons:

• Requires robust automated testing and CI/CD pipelines.
• Feature toggles add complexity for managing incomplete work in production.

Comparing the Workflows

Here’s a quick side-by-side comparison of these workflows:

Aspect	Gitflow Workflow	Git Feature Branch Workflow	Trunk-Based Development
Complexity	High	Moderate	Low
Use Case	Scheduled releases	Flexible projects	Continuous delivery
Branching Strategy	Multi-branch	Feature isolation	Single branch (trunk)
Release Management	Explicit release branches	None	Directly from main
Integration Frequency	Less frequent	Moderate	Frequent
Tools Needed	Minimal	Minimal	Robust CI/CD, toggles

Which Workflow Should You Choose?

The right workflow depends on your team’s needs:

• Gitflow Workflow is ideal for projects with scheduled releases or multiple production versions. It’s popular in enterprise environments where structure is critical.
• Git Feature Branch Workflow suits smaller teams or projects without rigid release schedules. It’s straightforward and integrates well with CI/CD pipelines.
• Trunk-Based Development works best for fast-moving teams focused on continuous delivery. It’s common in modern DevOps practices.

By understanding these workflows, you can better align your version control strategy with your project goals and team dynamics. Choose the one that empowers your team to deliver high-quality software efficiently. 

You might also find this post interesting:

Tech Bits: GitFlow vs GitLab Flow

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— Dr. Tree (@lannyland.com) December 31, 2024 at 12:44 PM

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