Kerry CorderoKISS IT Design Principle - Human Error Prevention
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Troubleshooting

Routing & Switching

Troubleshooting – Finding Laptop with only the IP Address

If you have access to the Cisco switch and know the IP address of the laptop, you can identify the...
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Code

Python – Check HTTPS Status Codes

# Author: Kerry Cordero # Version: 1.0.0 # Description: This script searches a text file "dr-dns.txt" for FQDNs, checks the...
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Routing & SwitchingSecurity

WHOIS Check Expiration

  whois cordero.me | grep -i 'expiry' Registry Expiry Date: 2027-07-17T21:24:32Z  ...
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Routing & Switching

STP – Tracking Down Topology Changes and the Importance of Setting the Root Bridge

Finding Spanning Tree Protocol (STP) topology changes in a network is not always straightforward. However, it is critical to identify...
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Routing & SwitchingServers

MTU 1500: Fragmentation after 1472 bytes “Packet needs to be fragmented but DF set”

Are you getting an error message that says, “Packet needs to be fragmented but DF set” or “Frag needed and...
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CodeServers

Powershell – Find all AD Domain Controllers

  Get-ADDomainController -Filter * | Select-Object Name, IPv4Address, Site, OperatingSystem  ...
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Servers

Powershell – Viewing and Logging IIS Sessions

The commands below are helpful when troubleshooting and could be beneficial when designing for scalability. They can easily be scripted...
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Routing & Switching

STP – Finding Who’s Sending BPDUs on the Network

Knowing which devices are sending BPDU packets on the network when troubleshooting spanning tree issues can be helpful. This allows...
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Security

TLS Verification and Testing

HOW TLS WORKS TLS version negotiation is typically performed as part of the SSL/TLS handshake process. When a client initiates...
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Laptops & DesktopsServers

Using CURL to get HTTP/S Status Codes

curl -Is https://{SITE}.com | head -1 HTTP/2 200 curl -Is https://{SITE}.com/login.asp | head -1 HTTP/2 404 curl -Is http://{SITE}.com |...
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Active Directory (AD) AWS Azure Best Practices BGP Certificates Cisco Cisco ACI Cisco ASA Cisco ASR Cisco Catalyst Cisco CLI Cisco ISE Cisco Nexus Cisco Stack DDOS Design DNS EIGRP F5 HTTP(S) IP Addressing and Subnetting LAG Microsoft IIS Microsoft SQL Microsoft Windows OSPF Packet Capture Palo Alto Palo Alto CLI PDF Planning Ports PowerShell python QOS Splunk SSL Storage Structured Cabling TCP TLS Troubleshooting Upgrade VMWare
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  • Home
  • About
  • Disclaimer
  • Guides and Slides
    • AWS Well-Architected Framework
    • Facebook – Running BGP in the Data Center at Scale
    • Microsoft – Experiences with BGP in Large Scale Data Centers
    • Palo Alto PCNSE Study Guide
  • IP Calculator
  • Links
  • Contact

Categories

  • Business Management
  • Cloud
  • Code
  • Data Center
  • Laptops & Desktops
  • Load Balancing
  • Routing & Switching
  • Security
  • Servers
  • Uncategorized
  • VOIP
  • Wireless

Tags

Active Directory (AD) AWS Azure Best Practices BGP Certificates Cisco Cisco ACI Cisco ASA Cisco ASR Cisco Catalyst Cisco CLI Cisco ISE Cisco Nexus Cisco Stack DDOS Design DNS EIGRP F5 HTTP(S) IP Addressing and Subnetting LAG Microsoft IIS Microsoft SQL Microsoft Windows OSPF Packet Capture Palo Alto Palo Alto CLI PDF Planning Ports PowerShell python QOS Splunk SSL Storage Structured Cabling TCP TLS Troubleshooting Upgrade VMWare
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