I created a subdomain called test.mysite1.com on the website mysite1.com, and added an entry of type A to the DNS hosting in mysite1.com with the value of 212.33.220.56.

However, even after 12 hours, when I checked my domain test.mysite1.com using the nslookup command, the IP address of the webhosting was still returned instead of the one I added.

I am wondering what could be causing this issue and why my IP address is not being substituted when referring to test.mysite1.com.

It's possible that the default TTL, or Time to Live, is set to 1 day instead of 12 hours, which could explain why the changes are not immediately reflected. You might consider changing the TTL to 3600, or 1 hour, if possible.

To ensure that the zone has been updated properly, it's advisable to check the serial before and after making any changes. The counter should increase by one with each change, indicating that the zone has been updated successfully.

You can use the following command to look at your nameserver and others: nslookup -q=soa mysite1.com 8.8.8.8.

It's worth noting that some DNS hosting services only allow subdomains to be added as part of the record name, rather than its full FQDN. This could potentially cause issues, such as in the case of test.mysite1.com.mysite1.com.

Are you looking to add an additional A-record for domain X that points to the IP address of domain Y hosted elsewhere, or create a subdomain for domain X via a CNAME record that will open on another hosting? For instance, aaa.x.com can be opened on a different hosting while x.com stays on the first hosting.

Alternatively, are you interested in using DNS to redirect users from domain X, which is currently hosted on the first server, to site Y on another hosting under a different domain name?

In the first scenario, if the domain is delegated to the ns of the hosting provider, then the host may need to redirect it independently through the hosting control panel or technical support.

There could be a few reasons why your IP address is not being substituted when referring to test.mysite1.com. Here are a few possibilities:

1. DNS Propagation: DNS changes can take time to propagate across the internet. While you mentioned waiting for 12 hours, it's possible that the changes haven't fully propagated yet. In some cases, it can take up to 24-48 hours for DNS changes to take effect worldwide.

2. TTL (Time-to-Live) Setting: The TTL value associated with the DNS record may be set to a higher value, causing the changes to take longer to propagate. The TTL value determines how long DNS resolvers should cache the record before checking for updates again. If the TTL is set to a high value, it could delay the propagation of your changes.

3. Caching: Your local machine or network may have cached the previous DNS resolution for test.mysite1.com. Caches are used to improve performance by storing frequently accessed data temporarily. Clearing your local DNS cache or using a different device/network can help bypass any caching issues.

4. DNS Resolution Order: It's possible that your DNS resolver is prioritizing a different DNS server over the one where you made the changes. This can happen if your device or network is configured to use a specific DNS server or if the resolver uses a predefined order for querying DNS servers.

5. Misconfiguration: Double-check if you have correctly configured the DNS entry. Make sure the entry is set up for the correct subdomain (test.mysite1.com) and the IP address matches what you expect (212.33.220.56). Additionally, ensure that you have saved the changes properly in your DNS hosting provider's control panel.

6. DNS Caching by ISPs: Internet Service Providers (ISPs) may also have their own DNS caching mechanisms. Even after updating your DNS records, some ISPs may cache the old DNS information for a longer period of time. Unfortunately, this is beyond your control as an end-user, and you need to wait for the cache to clear on the ISP's side.

7. DNS Hijacking: In rare cases, DNS hijacking can occur where an attacker intercepts the DNS resolution process and redirects the traffic to a different IP address. While uncommon, it's worth considering this possibility if you have ruled out all other potential causes.

8. DNS Zone Configuration: Ensure that the DNS zone configuration for mysite1.com is correctly set up to include the subdomain "test" and points to the correct DNS server. It's possible that there might be an issue with the overall DNS zone configuration, which is preventing the specific subdomain from resolving correctly.

To troubleshoot this issue further, you can try the following steps:
- Double-check the DNS entry on your DNS hosting provider's settings panel to ensure that it is correct.
- Verify with your DNS hosting provider if any additional steps are required for configuration updates to take effect.
- Temporarily disable any local firewalls, VPNs, or security software that might interfere with DNS resolution.
- Use an online DNS lookup tool from different locations to see if the changes are visible outside your network.
- Contact your DNS hosting provider's support for further assistance if the issue persists.