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I'm Carrie, a cybersecurity engineer and writer, working for SafeLine Team. SafeLine is a free and open source web application firewall, self-hosted, very easy to use.
When building a website, setting up a server, or managing web applications, it’s essential to understand what domains and wildcard domains are. They play a fundamental role in how users interact with your site and how you manage web content across different subdomains.
1. What is a Domain?
A domain is a unique name that identifies a website on the internet. It is part of the website's URL and consists of several levels:
- Top-Level Domain (TLD): The TLD is the extension at the end of the domain, such as .com, .org, .net, or .edu. Each TLD has its purpose. For instance, .com is often used for commercial sites, .edu for educational institutions, and .gov for government websites.
-
Second-Level Domain (SLD): This is the main part of your domain name and usually represents the brand or name of the website, like openai in
openai.com. -
Subdomain: A subdomain is added in front of the second-level domain to organize or separate sections of a website. For example, blog.openai.com is a subdomain of
openai.com.
The entire combination (subdomain, SLD, TLD) makes up the fully qualified domain name (FQDN), such as blog.openai.com.
2. What is a Wildcard Domain?
A wildcard domain allows you to apply the same settings (like security certificates or website configurations) to multiple subdomains of a main domain. This is done by placing an asterisk (*) in front of the main domain, signifying that any subdomain should be included under the same configuration.
For example, if you set up *.example.com as a wildcard domain, it would include:
www.example.comblog.example.comshop.example.com
…and any other subdomain under example.com without requiring separate configurations for each one.
3. Differences Between Standard Domains and Wildcard Domains
| Aspect | Standard Domain | Wildcard Domain |
|---|---|---|
| Purpose | Represents a single domain or website | Covers multiple subdomains |
| Subdomain Coverage | Does not automatically cover subdomains | Automatically covers all subdomains |
| Common Uses | Smaller sites, single-domain purposes | Large sites, SaaS platforms, multisite |
| Example | example.com |
*.example.com |
4. Why Use a Wildcard Domain?
Wildcard domains are useful when you have multiple subdomains and want to manage them under a single configuration. Here are some common use cases:
- Ease of Management: Rather than setting up individual configurations for each subdomain, a wildcard domain consolidates them under a single setup.
- SSL/TLS Certificates: Wildcard SSL certificates encrypt the connection for all subdomains, making it more efficient for sites with multiple areas that need to be secure.
-
Multi-Site Platforms: Wildcards are also ideal for SaaS applications, forums, or platforms that host numerous user-generated sites or pages on subdomains (e.g.,
user1.platform.com,user2.platform.com).
5. Setting Up Wildcard Domains
Setting up a wildcard domain is straightforward. Here’s how you generally proceed:
-
DNS Configuration: In your DNS settings, create a new record with an asterisk (
*) to signify any subdomain. For example, adding a wildcard DNS entry for*.example.comwill direct all subdomains to the same IP address. - SSL Certificates: You can obtain a wildcard SSL certificate from most Certificate Authorities (CAs), allowing you to secure all subdomains without needing individual certificates.
Example of DNS Configuration
- Go to your DNS settings on your domain registrar or hosting provider.
- Add an “A” record with the name
*and point it to your server's IP address. - Save your settings, and all subdomains of
example.comwill now resolve to the same server.
6. Pros and Cons of Wildcard Domains
Pros
- Simplifies Setup and Maintenance: Wildcard domains eliminate the need for configuring each subdomain separately.
- Reduces Costs: A single wildcard SSL certificate covers all subdomains, rather than purchasing multiple individual certificates.
- Scalability: As your site grows, wildcard domains support rapid addition of new subdomains without reconfiguration.
Cons
- Potential Security Risks: If an attacker gains control over the main domain, they can also create harmful subdomains.
-
Wildcard Limitations: Wildcards usually don’t support multiple levels (e.g.,
sub.sub.example.com).
7. Conclusion
Domains and wildcard domains are essential in web management, particularly for businesses or platforms that support multiple subdomains. While a standard domain is perfect for simpler websites, wildcard domains are ideal for large-scale, multi-subdomain setups that require secure and streamlined management.
Wildcard domains allow for efficient management, and tools like wildcard SSL certificates enhance the security and simplicity of managing encrypted subdomains. Whether you’re running a business website, hosting multiple sections, or building a SaaS platform, understanding domains and wildcard domains will give you more control over your online presence.
转载自：https://dev.to/carrie_luo1/understanding-domains-and-wildcard-domains-a-guide-for-beginners-1kdg
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