The US DOD researchers figured out a way to break up messages into smaller parts, and sending each part to the destination, whereupon reassembly of the original message would be possible. This is called the packet system.
In 1972, ARPANET developers created the first email message software for the purpose of communicating and coordinating projects
In 1984, DNS was introduced to give the world domain endings like .edu, .com, .gov, .org and other country codes.
A 3-way handshake
send-SYN
SYN-ACK
TCP ACK
Tuesday, March 6, 2012
Monday, March 5, 2012
HVAC and Power Rating Calculators
A quick link to find a Dell Energy Star rating calculator for heat generation and cooling requirements for Dell models for 48U, 42U or 24U Poweredge racks.
I was actually looking for the rating for one machine but it makes sense the application is making the calculations based on an entire rack. Launch the page for Dell Star Online here.
Another important factor to consider is how many units you can fit into the rack given the power available to the rack. Here is a useful answer for Dell Poweredge Server Power Requirements rated for PE 2950 as a starting point.
Check again for more information about Water Cooled Racks or High Performance Cooling solutions.
Whitepaper for Watts and Volt-Amps
I was actually looking for the rating for one machine but it makes sense the application is making the calculations based on an entire rack. Launch the page for Dell Star Online here.
Another important factor to consider is how many units you can fit into the rack given the power available to the rack. Here is a useful answer for Dell Poweredge Server Power Requirements rated for PE 2950 as a starting point.
Check again for more information about Water Cooled Racks or High Performance Cooling solutions.
Whitepaper for Watts and Volt-Amps
Doing My Own Cisco Tech Support
Cisco has a really good tech support hot line. I put in a TAC request for a pretty simple question about not being able to configure the serial port.
Create Serial Sub Interface Cisco 2811
"Hi. I can't access the serial port, was trying to configure serial 1/0 on my router cisco 2811 but I guess it does not exist?
The cisco online help says to try
Controller t1 0/0/0
Framing esf
Linecode b8zs
Channel-group 0 timeslots 1-24 speed 64
I did show controllers and all kinds of hardware descriptions pop up but not t1 specifically
The router didn't know what to do with the controller command, I checked the hardware but it does not have a serial port. Is that possible?"
I guess I could pause next time, and give the guy a chance to talk or take notes. Anyway I couldn't immediately provide the serial number on the unit cuz I wasn't logged in and I didn't have the service contract searchable right in front of me. So I mention that I will login and write up the TAC online. While clicking online and trying to find the TAC gui, I stumble upon the link for T1 HWIC cards, like the one that is NOT even plugged into to my unit. There is no WAN interface and link connected, the T1 truly does not exist!
I didn't even have a Cisco T1/ E1 WAN Interface Cards
Anywayz I feel rather silly about calling in the first place but now I have confirmed that the show controller command really works! Once again it is the USER error.
Create Serial Sub Interface Cisco 2811
"Hi. I can't access the serial port, was trying to configure serial 1/0 on my router cisco 2811 but I guess it does not exist?
The cisco online help says to try
Controller t1 0/0/0
Framing esf
Linecode b8zs
Channel-group 0 timeslots 1-24 speed 64
I did show controllers and all kinds of hardware descriptions pop up but not t1 specifically
The router didn't know what to do with the controller command, I checked the hardware but it does not have a serial port. Is that possible?"
I guess I could pause next time, and give the guy a chance to talk or take notes. Anyway I couldn't immediately provide the serial number on the unit cuz I wasn't logged in and I didn't have the service contract searchable right in front of me. So I mention that I will login and write up the TAC online. While clicking online and trying to find the TAC gui, I stumble upon the link for T1 HWIC cards, like the one that is NOT even plugged into to my unit. There is no WAN interface and link connected, the T1 truly does not exist!
I didn't even have a Cisco T1/ E1 WAN Interface Cards
Anywayz I feel rather silly about calling in the first place but now I have confirmed that the show controller command really works! Once again it is the USER error.
CCNA, ICND1 and ICND2 Practice Exams
I found a really good link on the Cisco Learning Network website for practice questions here.
There are questions for the six modules:
Module 1: OSI Layer and IP questions
Module 2: Hardware, bridges, Hubs
Module 3: WLAN
Module 4: IP addressing, IOS Commands, Routing basics
Module 5: WAN, nat
Module 6: cdp, hardware and memory
There are tabs and links to study modules, 15-20 training videos and lab simulations.
At the login page I also found an ad for a new "game". Cisco Aspire CCNA Edition! Practice for your Cisco CCNA exam by solving realistic networking problems. Seriously? That's a game?
The website Cisco Tests dot org also has a timed exam with pretty realistic questions! It's not for the ICND1 and ICND2 but it would cover the similar line of questioning if you just wanted a timed practise exam experience.
CCNA
There are questions for the six modules:
Module 1: OSI Layer and IP questions
Module 2: Hardware, bridges, Hubs
Module 3: WLAN
Module 4: IP addressing, IOS Commands, Routing basics
Module 5: WAN, nat
Module 6: cdp, hardware and memory
There are tabs and links to study modules, 15-20 training videos and lab simulations.
At the login page I also found an ad for a new "game". Cisco Aspire CCNA Edition! Practice for your Cisco CCNA exam by solving realistic networking problems. Seriously? That's a game?
The website Cisco Tests dot org also has a timed exam with pretty realistic questions! It's not for the ICND1 and ICND2 but it would cover the similar line of questioning if you just wanted a timed practise exam experience.
CCNA
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