Are you tired of dealing with mysterious domain name blockages on your VPN? Have you ever wondered why your alias domain name gets blocked on Zscaler and OpenVPN, but not on CNAME? You’re not alone! In this article, we’ll dive deep into the world of domain name resolution, VPNs, and DNS records to uncover the secrets behind this puzzling phenomenon.
An alias domain name, also known as a canonical name (CNAME), is a DNS record that maps an alias or alternate name to a canonical name. In simple terms, it’s a way to associate multiple names with a single IP address or domain name. For example, blog.example.com might be an alias for example.com. When a user types in blog.example.com, the DNS system redirects them to the canonical name, example.com.
VPNs, or Virtual Private Networks, create a secure and encrypted tunnel between your device and a VPN server. When you access a website through a VPN, your internet traffic is routed through this tunnel, and your IP address is masked. However, this isn’t the only thing that happens. Your DNS queries are also sent through the VPN tunnel, which can lead to unexpected behavior when it comes to domain name resolution.
Zscaler and OpenVPN are two popular VPN services that handle domain name resolution differently. While both services provide robust security features, their approaches to DNS resolution can lead to varying results.
Zscaler uses a proprietary DNS resolution mechanism that inspects and filters DNS traffic. This means that when you access a website through Zscaler, the VPN service sends your DNS queries to its own resolvers, which then forward the requests to the destination DNS servers. This can lead to issues with alias domain names, as Zscaler’s resolvers might not always respect the CNAME record and instead resolve the domain name to its canonical name.
OpenVPN, on the other hand, uses a more traditional approach to DNS resolution. When you connect to an OpenVPN server, your DNS queries are sent directly to the destination DNS servers, bypassing the VPN service’s resolver. This means that OpenVPN relies on the DNS infrastructure of the destination website, which can lead to more accurate resolution of alias domain names.
Now that we’ve discussed how Zscaler and OpenVPN handle domain name resolution, let’s explore why alias domain names might get blocked on these VPN services.
One common reason for blocked alias domain names is DNS record conflicts. When a VPN service’s resolver resolves an alias domain name, it might return a different IP address than the one associated with the canonical name. If the VPN service’s firewall or security rules block the resolved IP address, you might experience issues accessing the website.
Zscaler and OpenVPN employ various security measures to protect users from malicious websites and phishing attacks. These measures might include blocklists, IP reputation scoring, and domain reputation analysis. If an alias domain name is associated with a known malicious or suspicious domain, the VPN service might block access to it.
The configuration of the DNS server can also impact the resolution of alias domain names. If the DNS server is not properly configured to resolve CNAME records, the VPN service might not be able to resolve the alias domain name correctly, leading to blockages.
Don’t worry, we’ve got you covered! Here are some steps to help you unblock alias domain names on Zscaler and OpenVPN:
1. Check the Zscaler firewall rules: Verify that the resolved IP address of the alias domain name is not blocked by Zscaler’s firewall rules.
2. Configure the DNS server: Ensure that the DNS server is properly configured to resolve CNAME records.
3. Whitelist the alias domain name: Add the alias domain name to the whitelist to bypass Zscaler’s security measures.
1. Check the OpenVPN server configuration: Verify that the OpenVPN server is properly configured to forward DNS queries to the destination DNS servers.
2. Disable the OpenVPN firewall: Temporarily disable the OpenVPN firewall to see if it’s blocking the alias domain name.
3. Use a custom DNS resolver: Configure OpenVPN to use a custom DNS resolver that respects CNAME records.
Blocked alias domain names on VPNs can be frustrating, but by understanding how Zscaler and OpenVPN handle domain name resolution, you can take steps to unblock them. Remember to check DNS record conflicts, security measures, and DNS server configuration to ensure that your alias domain names are resolved correctly. If you’re still experiencing issues, try the troubleshooting steps outlined in this article.
| VPN Service | Domain Name Resolution Approach | Alias Domain Name Handling |
|---|---|---|
| Zscaler | Proprietary DNS resolution mechanism | Might block alias domain names due to DNS record conflicts or security measures |
| OpenVPN | Traditional DNS resolution approach | Might respect CNAME records, but can still block alias domain names due to firewall or security rules |
Q: Why do I need to configure my DNS server to resolve CNAME records?
A: Configuring your DNS server to resolve CNAME records ensures that your alias domain names are resolved correctly, reducing the likelihood of blockages.
Q: How do I whitelist an alias domain name on Zscaler?
A: You can whitelist an alias domain name on Zscaler by adding it to the whitelist section in the Zscaler administration portal.
Q: Can I use a custom DNS resolver with OpenVPN?
A: Yes, you can configure OpenVPN to use a custom DNS resolver that respects CNAME records. This can help ensure that your alias domain names are resolved correctly.
<code>
# OpenVPN configuration file
vpn.example.com {
...
dns-servers = 8.8.8.8 4.4.4.4
...
}
</code>
By following the steps and guidelines outlined in this article, you should be able to unblock alias domain names on Zscaler and OpenVPN. Remember to stay vigilant and monitor your DNS resolution and security measures to ensure seamless access to your favorite websites.
Want to learn more about DNS resolution and VPNs? Check out our extensive guide on DNS resolution and VPNs!
Frequently Asked Question
If you’re stuck with blocked alias domain names on your VPN(s) like Zscaler and OpenVPN, but not CNAME, we’ve got you covered!
Why are my alias domain names blocked on VPN(s) but not CNAME?
This is because VPN(s) like Zscaler and OpenVPN have DNS filtering and security policies in place to block alias domain names, which can be used for malicious activities. However, CNAME records are not affected as they are used to map an alias or alternate name to a canonical name, which is not considered a security risk.
How do VPN(s) like Zscaler and OpenVPN block alias domain names?
These VPN(s) use DNS filtering to block alias domain names by checking the DNS queries against a list of known malicious or unauthorized domains. If the query matches a blocked domain, the VPN will block the request and prevent the connection.
Can I whitelist my alias domain name on my VPN?
Yes, you can whitelist your alias domain name on your VPN by adding it to the allowed list or exceptions. This will allow the VPN to bypass the DNS filtering for that specific domain, allowing you to access it. However, this may vary depending on the VPN provider and their policies.
Why is CNAME not blocked by VPN(s) like Zscaler and OpenVPN?
CNAME records are not blocked because they are used for legitimate purposes such as mapping an alias to a canonical name, and are not considered a security risk. VPN(s) prioritize blocking malicious traffic over legitimate traffic, and CNAME records fall under the latter category.
What can I do if my alias domain name is blocked by my VPN?
If your alias domain name is blocked by your VPN, you can try whitelisting the domain, contacting your VPN provider for assistance, or using a different VPN that does not block alias domain names. Alternatively, you can also consider using a different DNS resolution method that is not blocked by your VPN.