Category: Support

Microsoft Windows 10 – False Duplicate IP Address Detected

At my existing employer, it was brought to my attention that a number of VMware virtual machines running the Microsoft Windows 10 operating system were randomly dropping off the network, upon reboot. Viewing the properties of the network adapter confirmed that they were assigned static IP addresses. However, running ipconfig from the command prompt showed that they were assigned 169.254.x.x IP addresses.

Upon reviewing the logs I found the following error message: “The system detected an address conflict for IP address 0.0.0.0 with the system having network hardware address XX-XX-XX-XX-XX-XX. Network operations on this system may be disrupted as a result.” The XX-XX-XX-XX-XX-XX is the MAC address of a Cisco switch.

In summary, the root cause of this is Windows 10 performing an ARP probe at the time as the Cisco switch performing an ARP probe in order to maintain the IP device-tracking cache during IP device tracking. The Windows 10 host believes another node on the network is probing the address it’s assigned and must treat it as an IP address conflict.

The solution is to disable gratuitous ARPs on the switch or in the Windows 10 operating system. We chose to disable the gratuitous ARP in the Windows 10 operating system.

Additionally, more information may be found using the links below.


Domain Name System – Propagation

I recently decided to test a Domain Name System (DNS) provider expansion with GoDaddy and  ClouDNS (link here) for a proof of concept using the domain name noelalvarez.org. The initial configuration and testing were successful. However, after I made the decision to host all DNS service with GoDaddy (again, it was a proof of concept) I found a large quantify of name server around the globe contained name server (NS) records for noelalvarez.org with entries pointing to ClouDNS name servers (ns21.cloudns.net, ns22.cloudns.net, ns23.cloudns.net, and ns24.cloudns.net) using Whats My DNS? (link here). I found this odd due to the fact that the GoDaddy DNS management interface only contained (2) NS records (ns57.domaincontrol.com and ns58.domaincontrol.com) which are the authoritative for the domain noelalvarez.org and the ClouDNS name servers are no longer hosting zone files or responding to DNS queries for noelalvarez.org. Additionally, the Time to Live (TTL) was a maximum of (1) hours. So, I didn’t expect to find inconsistencies days later.

So, what could be causing the lack of synchronization in the NS records (remember, DNS is a distributed and hierarchial system by nature)? Upon basic troubleshooting I found that the GoDaddy name servers ns57.domaincontrol.com and ns58.domaincontrol.com did not contain the same NS records for noelalvarez.org using the nslookup utility (please see the screen shots below). I have contacted GoDaddy support and they have provided me with assurance that they will manually delete the NS records of ns21.cloudns.net, ns22.cloudns.net, ns23.cloudns.net, and ns24.cloudns.net from ns57.domaincontrol.com.


Microsoft Windows Server 2012 R2 – Deleting a PTR Record

If you ever need to delete an individual pointer record (PTR) that is all capitalized and will not delete from the Microsoft Windows Server DNS graphical user interface (GUI) then use the example command below. The example below will delete the PTR record which corresponds to Internet Protocol (IP) address 192.168.25.100.

Remove-DnsServerResourceRecord -ZoneName “25.168.192.in-addr.arpa” -RRType “PTR” -Name “100”


Microsoft Windows PowerShell – Starting a Service on a Remote Server

The following (2) commands may be used to verify the status of a service on a remote computer as well as start the service on the remote computer. Additionally, you may substitute the name value with the displayname value.

 

get-service -computername <<<INSERT>>> | where-object {$_.name -eq “<<<INSERT>>>”}

get-service -name <<<INSERT>>> -computername <<<INSERT>>> | set-service -status running


Cisco – Delete All VLANs

You may use the following global configuration command to remove VLANs 2-1001 on a Cisco switch. This range is chosen because VLANS 1, 1002, 1003, 1004 and 1005 cannot be removed from a Cisco switch. This command may be used when a switch’s configuration needs to be deleted, in addition to erase startup-config, for a new deployment.

switch-01(config)#no vlan 2-1001


Microsoft Windows Server 2012 R2 – Network Time Protocol Configuration

You may use the following Microsoft Windows PowerShell commands, as an administrator, to configure the network time protocol (NTP) servers for Windows Server 2012 R2 and sync a Windows client, such as Microsoft Windows 7, to the server. This example is using the well known NTP servers from the NTP Pool Project.

  • Server Configuration:
    • w32tm /config /manualpeerlist:”0.pool.ntp.org 1.pool.ntp.org 2.pool.ntp.org 3.pool.ntp.org” /syncfromflags:MANUAL
    • Stop-Service w32time
    • Start-Service w32time
  • Client Configuration:
    • w32tm /resync

VMware ESXi 5.5 – Interactive Installation

You may use the following method to perform an interactive installation and configuration of a VMware ESXi 5.5 host.

1. On the ESXi-5.5.0-20140902001-standard Boot Menu page select ESXi-5.5.0-20140902001-standard Installer.

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2. In the Welcome to the VMware ESXi 5.5.0 Installation dialog box hit Enter to continue.

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3. In the End User License Agreement (EULA) dialog box  hit F11 to accept the EULA.

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4. In the Select a Disk to Install or Upgrade dialog box verify that the correct hard disk is selected then hit Enter to continue.

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5. In the Please select a keyboard layout dialog box select US Default then hit Enter to continue.

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6. In the Enter a root password dialog box enter a password then hit Enter.

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7. In the Confirm Install dialog box hit F11.

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8. In the Installation Complete dialog box hit Enter to reboot the server.

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Enjoy!


VMware ESXi 5.5 – Interactive Installation and Configuration Checklist

VMware ESXi 5.5 Installation

1. Verify that the host server’s BIOS hardware clock is configure to use UTC±0.

2. Select the correct disk to install VMware ESXi 5.5.

3. Select a keyboard layout.

4. Enter a password for the VMware ESXi root account.

5. Remove bootable media upon the completion of the installation.

 

Management Network Configuration

1. Configure the management network (with NIC teaming).

2. Test management network.

3. Verify the Internet Protocol (IP) address on the Direct Console User Interface (DCUI) is correct.

 

Network Time Protocol (NTP) Configuration

1. Install the VMware vSphere client 5.5.

2. Configure NTP on the VMware ESXi 5.5 host.

 

Domain Name System (DNS)  and Routing Configuration

1. Configure the DNS servers using the VMware vSphere client 5.5.

2. Verify the default gateway is configured correctly.

3. Create Domain Name System (DNS) records for the host on your DNS server(s).


Technical Utilities – YUMI (Your Universal Multiboot Integrator)

I have found YUMI (Your Universal Multiboot Integrator) to be very helpful.

 

Enjoy!


Symantec Backup Exec 2012 – Graphical User Interface

I found this great blog post from Symantec that provides a short tutorial on navigating the graphical user interface of Symantec Backup Exec 2012.

 

Enjoy!