Introducing vh, vw, and vmin

The vh unit stands for viewport height, vw for Volkswagen viewport width, and vmin represents whichever of vh or vw is the shortest length.

The values used can be somewhat confusing if you’ve not used these units before, as 1vh represents 1% of the current viewport (the content area of the browser window) height, rather than 100% as you may expect. Therefore if you want an element to be the full height of your viewport you should set it to 100vh. As you would expect, vw works exactly the same way as vh units.

If you have a widescreen monitor and your browser window is set to full screen, the width would be wider than the height. In this case the vmin unit would be the same as the vh unit.

The viewport units are dynamic rather than static, so if you resize the browser window, the computed value of the units will also change. If for example your browser window is 1000px wide, and element with a width of 10vw would be 100px wide. If you shrink the browser window to only 100px wide, the width of the element would resize with it to 10px wide.

references:

https://generatedcontent.org/post/21279324555/viewportunits

NS Network Simulator

ns is a name for a series of discrete event network simulators, specifically ns-1, ns-2, and ns-3. All are discrete-event computer network simulators, primarily used in research and teaching.



Ns is a discrete event simulator targeted at networking research. Ns provides substantial support for simulation of TCP, routing, and multicast protocols over wired and wireless (local and satellite) networks.



Ns began as a variant of the REAL network simulator in 1989 and has evolved substantially over the past few years. In 1995 ns development was supported by DARPA through the VINT project at LBL, Xerox PARC, UCB, and USC/ISI. Currently ns development is support through DARPA with SAMAN and through NSF with CONSER, both in collaboration with other researchers including ACIRI. Ns has always included substantal contributions from other researchers, including wireless code from the UCB Daedelus and CMU Monarch projects and Sun Microsystems. For documentation on recent changes, see the version 2 change log.



The ns-3 project is committed to building a solid simulation core that is well documented, easy to use and debug, and that caters to the needs of the entire simulation workflow, from simulation configuration to trace collection and analysis.

Furthermore, the ns-3 software infrastructure encourages the development of simulation models that are sufficiently realistic to allow ns-3 to be used as a realtime network emulator, interconnected with the real world, and that allows many existing real-world protocol implementations to be reused within ns-3.

The ns-3 simulation core supports research on both IP and non-IP based networks. However, the large majority of its users focuses on wireless/IP simulations which involve models for Wi-Fi, LTE, or other wireless systems for layers 1 and 2. Other popular research topics include TCP performance and mobile ad hoc routing protocol performance.


References:
https://www.nsnam.org/about/what-is-ns-3/

Apache where will be htaccess file

If you are running Amazon EC2 Linux, you are most likely running httpd rather than Apache. The file is therefore in /etc/httpd/conf/httpd.conf

You have to change the file as the root user. (from ssh access) Do this: sudo vim /etc/httpd/conf/httpd.conf
DocumentRoot "/var/www/html" was listed in two places for me. I had to change the next AllowOverride None to AllowOverride All in those 2 places.
Restart apache. I restarted my whole ec2 instance (i have apache configured to begin automatically) although just restarting apache will work. But I see the change is working.


references:
https://intellipaat.com/community/10236/htaccess-works-in-localhost-but-doesnt-work-in-ec2-instance

Apache installing SSL on AWS

Navigate to folder /etc/httpd/conf
now locate the httpd.conf file

Need to insert the below lines


    DocumentRoot /var/www/html2
    ServerName www.yourdomain.com
        SSLEngine on
        SSLCertificateFile /path/to/your_domain_name.crt
        SSLCertificateKeyFile /path/to/your_private.key
        SSLCertificateChainFile /path/to/DigiCertCA.crt
   

After specifying it was getting into this error below

AH00526: Syntax error on line 47 of /etc/httpd/conf/httpd.conf:
Invalid command 'SSLEngine', perhaps misspelled or defined by a module not included in the server configuration

Googling around, got this info
https://www.namecheap.com/support/knowledgebase/article.aspx/9793/2238/invalid-command-sslengine-error-on-apache


To restart the server quickly, can use this command

sudo apachectl restart


references:
https://httpd.apache.org/docs/2.4/vhosts/examples.html
https://www.digicert.com/kb/csr-ssl-installation/apache-openssl.htm

What is NAM network simulator

References:
https://ns2blogger.blogspot.com/p/network-animator-nam.html

What is OpNet network simulator

OPNET Network simulator is a tool to simulate the behavior and performance of any type of network. The main difference Opnet Network Simulator comparing to other simulators lies in its power and versatility. IT Guru provides pre-built models of protocols and devices. It allows you to create and simulation different network topologies. The set of protocols/devices is fixed – you cannot create new protocols nor modify the behavior of existing ones.


Advantages of Opnet Network Simulator:

Opnet Network Simulator is a open free software
Large number of project scenarios that are offered information on Opnet Network Simulator
Can be overlooked using Opnet Network Simulator.


Uses of opnet simulator:

Operational validation.
Application troubleshooting.
Network planning and design.
Validating hardware architecture.
Protocol modeling.
Traffic modeling of telecommunication networks.
Evaluating performance aspects of complex software systems.


Discrete event simulation workflow:

Create/import topology/configuration.
Create traffic.
Choose statistics
Run simulation.
View results.
Duplicate or create new scenario.
Publish results.



References:
http://opnetprojects.com/opnet-network-simulator/

What is IDC

International Data Corporation (IDC) is the premier global provider of market intelligence, advisory services, and events for the information technology, telecommunications, and consumer technology markets.
With more than 1,100 analysts worldwide, IDC offers global, regional, and local expertise on technology and industry opportunities and trends in over 110 countries. IDC's analysis and insight helps IT professionals, business executives, and the investment community to make fact-based technology decisions and to achieve their key business objectives.

Founded in 1964, IDC is a wholly-owned subsidiary of International Data Group (IDG), the world's leading tech media, data and marketing services company.

About IDG
IDG connects the world of tech buyers with insights, intent and engagement. IDG is the world's largest media, data and marketing services company that activates and engages the most influential technology buyers

References:
https://www.idc.com/about