DNS Error When Using URLfetchapp For A URL With = String / URL With Potential Redirect Issue

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Introduction

When working with Google Apps Script, particularly with the URLFetchApp service, you may encounter a DNS error when trying to fetch a URL that contains an "=" string or a URL with potential redirect issues. This issue can be frustrating, especially when you're trying to automate tasks or fetch data from external sources. In this article, we'll explore the possible causes of this DNS error and provide some solutions to help you resolve the issue.

Understanding DNS Errors

A DNS (Domain Name System) error occurs when the DNS server is unable to resolve a domain name to an IP address. This can happen for various reasons, such as:

  • DNS Server Issues: The DNS server may be experiencing technical difficulties, causing the domain name to be unresolved.
  • Domain Name Issues: The domain name may be misspelled, or there may be a problem with the domain name's configuration.
  • Firewall or Network Issues: Firewalls or network configurations may be blocking access to the domain name.

URLFetchApp and DNS Errors

When using URLFetchApp to fetch a URL, you may encounter a DNS error if the URL contains an "=" string or has potential redirect issues. This is because URLFetchApp uses the URL class to parse the URL, and if the URL contains an "=" string, it may be misinterpreted as a query parameter.

Causes of DNS Errors with URLFetchApp

There are several possible causes of DNS errors when using URLFetchApp:

  • URL with "=" String: If the URL contains an "=" string, it may be misinterpreted as a query parameter, causing the DNS error.
  • URL with Potential Redirect Issues: If the URL has potential redirect issues, such as a redirect loop or a redirect to a non-existent domain, it may cause a DNS error.
  • Domain Name Issues: If the domain name is misspelled or has a problem with its configuration, it may cause a DNS error.

Solutions to DNS Errors with URLFetchApp

To resolve DNS errors when using URLFetchApp, you can try the following solutions:

  • Use a Different URL: If the URL contains an "=" string, try using a different URL that does not contain the "=" string.
  • Use a URL with a Different Protocol: If the URL has potential redirect issues, try using a URL with a different protocol, such as https instead of http.
  • Check the Domain Name: Make sure the domain name is spelled correctly and has no problems with its configuration.
  • Use a Proxy Server: If the DNS error is caused by a firewall or network issue, try using a proxy server to bypass the issue.
  • Use a Different DNS Server: If the DNS error is caused by a DNS server issue, try using a different DNS server to resolve the domain name.

Example Code

Here is an example code snippet that demonstrates how to use URLFetchApp to fetch a URL and handle DNS errors:

function fetchUrl(url) {
  try {
    var response = UrlFetchApp.fetch(url);
    var content = response.getContentText();
    return content;
  } catch (error) {
    if (error.getMessage().includes("DNS")) {
      Logger.log("DNS error occurred: " + error.getMessage());
      return null;
    } else {
      throw error;
    }
  }
}

Conclusion

In conclusion, DNS errors can occur when using URLFetchApp to fetch a URL that contains an "=" string or has potential redirect issues. By understanding the possible causes of DNS errors and using the solutions provided in this article, you can resolve the issue and successfully fetch the URL using URLFetchApp.

Additional Information

UPDATE

I discovered that the entire domain https://www.mots.go.th appears to give DNS error when using urlfetchapp, not just this specific page. Perhaps this is some sort of protection mechanism in place to prevent abuse or unauthorized access to the domain.

Related Topics

  • Google Apps Script: Google Apps Script is a cloud-based scripting platform that allows you to automate tasks and create custom applications.
  • URLFetchApp: URLFetchApp is a service in Google Apps Script that allows you to fetch URLs and retrieve data from external sources.
  • DNS: DNS (Domain Name System) is a system that translates domain names into IP addresses.

References

Introduction

In our previous article, we discussed the issue of DNS errors when using URLFetchApp to fetch a URL that contains an "=" string or has potential redirect issues. In this article, we'll provide a Q&A section to help you better understand the issue and its solutions.

Q: What is a DNS error?

A: A DNS (Domain Name System) error occurs when the DNS server is unable to resolve a domain name to an IP address. This can happen for various reasons, such as DNS server issues, domain name issues, or firewall or network issues.

Q: Why do I get a DNS error when using URLFetchApp?

A: You may get a DNS error when using URLFetchApp if the URL contains an "=" string or has potential redirect issues. This is because URLFetchApp uses the URL class to parse the URL, and if the URL contains an "=" string, it may be misinterpreted as a query parameter.

Q: How can I resolve a DNS error when using URLFetchApp?

A: To resolve a DNS error when using URLFetchApp, you can try the following solutions:

  • Use a different URL that does not contain the "=" string.
  • Use a URL with a different protocol, such as https instead of http.
  • Check the domain name to ensure it is spelled correctly and has no problems with its configuration.
  • Use a proxy server to bypass firewall or network issues.
  • Use a different DNS server to resolve the domain name.

Q: What is the difference between a DNS error and a URLFetchApp error?

A: A DNS error occurs when the DNS server is unable to resolve a domain name to an IP address, while a URLFetchApp error occurs when there is a problem with the URLFetchApp service or the URL being fetched.

Q: How can I handle DNS errors in my Google Apps Script code?

A: You can handle DNS errors in your Google Apps Script code by using a try-catch block to catch the error and handle it accordingly. For example:

function fetchUrl(url) {
  try {
    var response = UrlFetchApp.fetch(url);
    var content = response.getContentText();
    return content;
  } catch (error) {
    if (error.getMessage().includes("DNS")) {
      Logger.log("DNS error occurred: " + error.getMessage());
      return null;
    } else {
      throw error;
    }
  }
}

Q: Can I use a different DNS server to resolve the domain name?

A: Yes, you can use a different DNS server to resolve the domain name. You can specify the DNS server to use in your URLFetchApp code by using the dns parameter. For example:

function fetchUrl(url, dns) {
  var options = {
    'method': 'GET',
    'headers': {
      'Authorization': 'Bearer YOUR_API_KEY'
    },
    'dns': dns
  };
  var response = UrlFetchApp.fetch(url, options);
  var content = response.getContentText();
  return content;
}

Q: What are some common causes of DNS errors?

A: Some common causes of DNS errors include:

  • DNS server issues
  • Domain name issues
  • Firewall or network issues
  • Redirect issues

Q: How can I troubleshoot DNS errors?

A: To troubleshoot DNS errors, you can try the following steps:

  • Check the domain name to ensure it is spelled correctly and has no problems with its configuration.
  • Use a different DNS server to resolve the domain name.
  • Check the firewall or network configuration to ensure it is not blocking access to the domain name.
  • Use a proxy server to bypass firewall or network issues.

Conclusion

In conclusion, DNS errors can occur when using URLFetchApp to fetch a URL that contains an "=" string or has potential redirect issues. By understanding the possible causes of DNS errors and using the solutions provided in this article, you can resolve the issue and successfully fetch the URL using URLFetchApp.