Event Grid DNS Resolution Failure for Belgium Central Region - Hostname Not Found

Question

Event Grid DNS Resolution Failure for Belgium Central Region - Hostname Not Found

Olivier 0

We are experiencing DNS resolution failures when attempting to connect to Azure Event Grid endpoints in the Belgium Central region. The issue appears to be related to the endpoint suffix numbering.

Issue Details:

Error Message: getaddrinfo ENOTFOUND *.belgiumcentral-0.eventgrid.azure.net
Region: Belgium Central
SDK: @azure/eventgrid (Node.js)
Authentication: AzureKeyCredential

Root Cause Hypothesis:

We believe we may be using an incorrect suffix (-0 instead of -1) for the Belgium Central endpoint. When attempting to correct this to -1, we still encounter DNS resolution errors.

SSL Certificate Observations:

The SSL certificate presented by Azure includes these altnames:

DNS:*.global-1.eventgrid.azure.net
DNS:*.belgiumcentral-1.eventgrid.azure.net
DNS:*.eventgrid.azure.net

This suggests the endpoint should use -1 suffix, but DNS resolution still fails with that pattern.

Working Regional Endpoints:

Other regions work correctly with the -1 suffix pattern:

West Europe: *.westeurope-1.eventgrid.azure.net ✅
Germany West Central: *.germanywestcentral-1.eventgrid.azure.net ✅
France Central: *.francecentral-1.eventgrid.azure.net ✅

Questions:

What is the correct endpoint suffix for Belgium Central region (-0, -1, or something else)?
Is the Belgium Central Event Grid endpoint fully provisioned and available?
Why does the SSL certificate include *.belgiumcentral-1.eventgrid.azure.net if DNS resolution fails?
Is there a documented list of all regional Event Grid endpoints and their correct suffixes?

Code Pattern:

// Attempt 1: Using -0 suffix
const endpoint1 = "https://*.belgiumcentral-0.eventgrid.azure.net/api/events";
// Result: SSL certificate mismatch (cert expects -1)

// Attempt 2: Using -1 suffix
const endpoint2 = "https://*.belgiumcentral-1.eventgrid.azure.net/api/events";
// Result: getaddrinfo ENOTFOUND (DNS doesn't resolve)

const client = new EventGridPublisherClient(
    endpoint2,
    "EventGrid",
    new AzureKeyCredential(apiKey)
);

await client.send([{ /* event data */ }]);

Pravallika KV 12,730 Reputation points Microsoft External Staff Moderator

2026-02-02T12:28:10.4433333+00:00
Hi Olivier,

Thanks for reaching out to Microsoft Q&A.

DNS Resolution Failure:

Endpoint Suffix: Based on your observations, you're correct in noting that endpoints for Azure Event Grid in the Belgium Central region should typically use the -1 suffix, as shown in the SSL certificate. However, if you're still encountering the getaddrinfo ENOTFOUND error when using the -1 suffix, it may indicate a connectivity issue rather than just an incorrect endpoint.

SSL Certificate: The SSL certificate you listed including the *.belgiumcentral-1.eventgrid.azure.net suggests that -1 is indeed the correct suffix. If you're receiving a DNS resolution failure with this, it could indicate an issue with DNS propagation or configuration, especially if it works fine with other regions.

Troubleshooting Steps:

Check Azure Status: First, verify that Azure Event Grid is operational in the Belgium Central region by checking the Azure status dashboard. If there are ongoing issues, that might explain the failures.

Network Connectivity: Ensure that your network configuration allows outbound traffic to Azure services. This can often be impacted by firewall settings or network security groups. You can find guidance on this in the Troubleshoot connectivity issues.

Diagnostic Logs: Enabling diagnostic logs for your Event Grid topic can provide valuable information about the failures you're experiencing. Here's a guide on how to enable and view Diagnostic logs.

Update:

Eventually went ahead and chose a different region to host on. The -0 suffix URL for the Belgium region was obtained directly from Azure (copied the URL), so it appears that either the bootstrapping of the resource or the SSL certificate is incorrect.

Hope this helps!

1 answer

Your answer

Pravallika KV 12,730 Reputation points Microsoft External Staff Moderator

2026-02-02T12:28:10.4433333+00:00

Hi Olivier,

Thanks for reaching out to Microsoft Q&A.

DNS Resolution Failure:

Endpoint Suffix: Based on your observations, you're correct in noting that endpoints for Azure Event Grid in the Belgium Central region should typically use the -1 suffix, as shown in the SSL certificate. However, if you're still encountering the getaddrinfo ENOTFOUND error when using the -1 suffix, it may indicate a connectivity issue rather than just an incorrect endpoint.

SSL Certificate: The SSL certificate you listed including the *.belgiumcentral-1.eventgrid.azure.net suggests that -1 is indeed the correct suffix. If you're receiving a DNS resolution failure with this, it could indicate an issue with DNS propagation or configuration, especially if it works fine with other regions.

Troubleshooting Steps:

Check Azure Status: First, verify that Azure Event Grid is operational in the Belgium Central region by checking the Azure status dashboard. If there are ongoing issues, that might explain the failures.

Network Connectivity: Ensure that your network configuration allows outbound traffic to Azure services. This can often be impacted by firewall settings or network security groups. You can find guidance on this in the Troubleshoot connectivity issues.

Diagnostic Logs: Enabling diagnostic logs for your Event Grid topic can provide valuable information about the failures you're experiencing. Here's a guide on how to enable and view Diagnostic logs.

Update:

Eventually went ahead and chose a different region to host on. The -0 suffix URL for the Belgium region was obtained directly from Azure (copied the URL), so it appears that either the bootstrapping of the resource or the SSL certificate is incorrect.

Hope this helps!

Answer 1

Hello

That ENOTFOUND is happening because * can’t be used as a real hostname in an HTTP request. Your OS DNS resolver is literally trying to resolve a host named * (asterisk), which will always fail.

What you must pass to EventGridPublisherClient is the exact Topic Endpoint for your topic, which looks like:

https://<your-topic-name>.<region>-1.eventgrid.azure.net/api/events

…and you should fetch it from Azure, not construct it by hand. Microsoft’s doc shows getting it from the topic resource (Portal or CLI):
https://learn.microsoft.com/en-us/azure/event-grid/post-to-custom-topic

import { EventGridPublisherClient, AzureKeyCredential } from "@azure/eventgrid";

const endpoint = process.env.EVENTGRID_TOPIC_ENDPOINT!;
// Example value (from Azure): https://mytopic.westeurope-1.eventgrid.azure.net/api/events

const client = new EventGridPublisherClient(
  endpoint,
  "EventGrid",
  new AzureKeyCredential(process.env.EVENTGRID_KEY!)
);

await client.send([{ id: "1", eventType: "test", subject: "demo", eventTime: new Date(), data: { hello: "world" }, dataVersion: "1.0" }]);

If you replace * with your real topic name and it still says ENOTFOUND then it’s a genuine DNS/service availability issue for that region/endpoint . In that case the next check is: run nslookup <topic>.<region>-1.eventgrid.azure.net from another network/VM to confirm it’s not local DNS, and consider deploying the topic in a different region as a workaround while you open a Microsoft support ticket.

Olivier 0 Reputation points

2026-02-02T11:09:50.82+00:00

Hi,

Thanks for the clarification! Apologies for the earlier sanitized info with asterisks, we are using the actual topic name in the endpoint, not a wildcard.

To clarify:

We are constructing the endpoint as https://<topic>.belgiumcentral-0.eventgrid.azure.net/api/events using the endpoint provided by Azure.

When we run nslookup``https://<topic>.belgiumcentral-0.eventgrid.azure.net/api/events, it resolves correctly, so DNS is not the issue.

However, when connecting, we get an SSL certificate error: the certificate presented does not match the hostname (the cert’s altnames don’t include our topic endpoint, only wildcards like *.eventgrid.azure.net and *.belgiumcentral-1.eventgrid.azure.net).

So, to summarize:

DNS resolves fine for the topic endpoint.

The SSL certificate returned by Azure does not match the topic endpoint, causing the connection to fail.

Is there a step we’re missing in the topic setup, or is there a known issue with SSL certificates for Event Grid topics in this region? Any guidance would be appreciated!

Thanks!

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Event Grid DNS Resolution Failure for Belgium Central Region - Hostname Not Found

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