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Validating Network Connectivity Before Discovery

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In this lesson, you will learn:

  • Why an approved rule isn’t enough
  • How to test each port matrix row
  • How to record results

🔁 Quick look back: Last time: Validating DNS Resolution from the MID Host. You learned how to check DNS from each MID Server host.

1 The Problem: An Approved Rule Isn’t Always an Open Port

Ravi marked the Mumbai rules ‘done’. But sometimes:

  • A rule is on the wrong firewall.
  • A host firewall on the server still blocks the port.

🎯 The problem: An approved firewall rule isn’t always an open port.

👉 The fix: Test every port matrix row from the MID host, and record the result.

Table of connectivity tests.
Figure 1. Connectivity tests from snwr-mid-mum-01.

2 How to test

  • Use simple tools on the MID host to test a TCP port.
  • For SNMP, send a test query with the approved credential.
  • Test a few targets per zone, not just one.
  • Test the instance connection too.

💡 Good to know: Record the date, target, port and result. That’s your evidence if something breaks later.

3 When a test fails

Tell the rule’s owner with the exact source, target and port. If a host firewall blocks it, tell the server owner.

4 Project Clear View: How We Implemented It

📍 Situation: Ravi said the Mumbai rules were open.

🧭 Decision: Test every row from the MID host before the readiness check.

🛠️ Steps we took:

  1. Tested each port matrix row for Mumbai.
  2. Found one Windows server blocking port 135 in its own firewall.
  3. Sent the details to Priya.
  4. Retested after her fix.

✅ What we verified:

  • All Mumbai rows are ‘tested’.
  • The one failure was a host firewall, now fixed.

📁 Evidence: Connectivity test log, PR-12 in the tracker.

5 Quick recap

  • An approved rule isn’t proof the port is open.
  • Test each row from the MID host.
  • Record date, target, port and result.
  • Send failures to the right owner with exact details.

6 Check yourself

Think of your answer first. Then tap to check.

1 Why test after Ravi says the rules are open? Show answer

The rule could be on the wrong firewall, or a host firewall could still block it.

2 What did SNWR’s test find? Show answer

One Windows server blocking port 135 in its own host firewall.

3 Why record test results? Show answer

They’re evidence if something breaks later.

Nice work! SNWR’s network paths are proven. 🎉
Next up: Validating Pattern Commands and sudo Permissions

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