Category Archives: Networking

How can I see Time-To-Live (TTL) for a DNS record?

There are two ways that you can query a TTL value for a DNS record. You can use nslookup with the the -q=wks option. You can also view the TTL value in the local “DNS Resolver Cache” on the local … Continue reading →...

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Microsoft Network Monitor 3.4 Network capture filters

I’m a big fan of WireShark but recently found myself using Microsoft Network Monitor more as we have it installed on a lot of Web servers. Here is a list of filters that i found useful. Some of these filters … Continue reading →...

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Blocking an IP without a Windows firewall route NULL

Blocking an Outbound connection I have ran into a situation where a server was sending malformed requests to another server. The Windows firewall was turned off on this server, I did not want to turn it on as there is … Continue reading →...

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Capture Network Traffic with netsh trace command

A very useful netsh capture command when you are not able to install Wireshark or Micorosft Network Monitor app inside a server. Windows has a built in command that allows you to capture network traffic. To start capturing (Run command … Conti...

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Powershell script to test TCP port connectivity

I recently ran into an issue where a site kept going up and down and it was difficult to determine where the issue is. I used the script to validate if the F5 load balanced VIP was going down or … Continue reading →...

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How to redirect a port using netsh interface portproxy command in Windows

When you run the below command on your local desktop. -Your Desktop will start to listen on port 443 on all IPs (0.0.0.0) -Any connection that comes to your Desktop IP on port 443 will be forwarded to the following … Continue reading →...

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Citrix Netscaler: Configuring HTTPS load balancing

I finally got a chance to set up and configure a Citrix Netscaler appliance to load balance two websites.  In this setup the Netscaler will load balance two SSL (HTTPS) web servers with end-to-end encryption. I did run into some … Continu...

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iPerf Network performance comparison between Virtual Machines on ESXi6

I finally found some time to run a series of iPerf network performance tests between Windows server 2008 R2, Windows 2012 and a Linux Debian virtual machines. The tests compare bandwidth throughput between vmxnet3, e1000 going through a 1Gbit and &he...

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Detecting Ephemeral Port Exhaustion in Windows 7 / 8 / 2012

Ephemeral ports are ports that start at a higher range then regular ports. For example when compared to a web server that listens on port 80, ephemeral ports start from 49152 for Windows 2008 R2.  If there are scripts or … Continue reading &r...

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How to set up a Microsoft Network Load Balancing (NLB) in Windows 2008 R2

OVERVIEW Here is a quick guide how to set up two Web Servers that will be serving out the same web page for redundancy and load balancing purposes.  When we go to www.mywebsite.com address, the name will resolve to the Load Balancing … Cont...

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