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We take the water we drink for granted every day. We do not usually try to find out if the water that we are drinking is safe, we just assume that it is. Contaminated water supplies are starting to become more common stories that are being told. With these stories comes an awareness of possibly unsafe water. It is now time to start asking the questions that need to be asked.

Water Treatment Systems - What Are They?

To make the quality of your water improve, water treatment systems are what you need. These systems are designed to reduce or completely remove any and all contaminants in the drinking water. Water treatment systems can provide you with healthy and safe water that you will be able to drink.

The Different Types Of Water-Borne Nastiness?

One of the more important things to remember about the water you use is that it is never totally just water. If the water you are drinking states that it is pure, it will have some compounds, like minerals, that are safe for your health and do not cause any problems.

The contaminants that can cause health problems that do not come in the water naturally exist also. These contaminants are so dangerous, plants, animals, and humans can die from drinking this water.

Contaminants that are water-borne are each unique in the way they are made and also in the way they act. Contaminants in the water may include the chemicals arsenic, lead, pesticides, and some others that are dangerous to the health and safety of the user. Water treatment system usage will depend greatly on two main factors.

Methods Of Proper Water Treatment

The types of water treatment systems that we have available to us are so diverse. Those products that are available for commercial use are listed below:

* Disinfection by chlorine
* Treatment by ultra-violet light
* Cation exchange or treatment to soften water
* Steam distillation
* Filtration by membrane or osmosis in reverse
* Filtration that neutralizes
* Filtration that oxidizes
* Filtration by activated carbon
* Filtration by sedimentation or mechanical use

The Right Choice For Systems To Treat The Water

You will definitely be able to find small systems for water treatment that can fit into your household. Shopping for the right one can bring you to two types of systems; the point of entry and the point of use system.

The system that is known as the point of entry system treats all the water that comes from the main source. This is placed where all the water enters the home. These systems filter by sedimentation, offer a treatment for controlling iron, use chlorination, and soften the water.

The point of use system of treatment, only cleans the water that comes from select places in your home. This would be like a kitchen or bathroom faucet. It targets only one point of water entry and not the whole system. Only the water that flows from that particular outlet will be clean and safe for humans to drink.

Conditioning systems are not the same as a water treatment system. Conditioning systems only address the water problems such as bad taste, bad smells, and the color of the water. Water treatment systems reduce the amount of contaminants that are found in the water and thus reduce the hazards of the water.

You can also find more info on water treatment and extensive water treatment. eWaterTreatmentSystems.com is a comprehensive resource for water treatment with information on reviews, reverse osmosis and how it works.

Your CCNA certification exam is likely going to contain questions about Telnet, an application-level protocol that allows remote communication between two networking devices. With Telnet use being as common as it is, you had better know the details of how to configure it in order to pass your CCNA exam and to work in real-world networks.

The basic concept is pretty simple - we want to configure R1, but we're at R2. If we telnet successfully to R1, we will be able to configure R1 if we've been given the proper permission levels. In this CCNA case study, R2 has an IP address of 172.12.123.2 and R1 an address of 172.12.123.1. Let's try to telnet from R2 to R1.

R2#telnet 172.12.123.1

Trying 172.12.123.1 ... open

Password required, but none set

[Connection to 172.12.123.1 closed by foreign host]

This seems like a problem, but it's a problem we're happy to have. A Cisco router will not let any user telnet to it by default. That's a good thing, because we don't want just anyone connecting to our router! The "password required" message means that no password has been set on the VTY lines on R1. Let's do so now.

R1(config)#line vty 0 4

R1(config-line)#password baseball

A password of "baseball" has been set on the VTY lines, so we shouldn't have any trouble using Telnet to get from R2 to R1. Let's try that now.

R2#telnet 172.12.123.1

Trying 172.12.123.1 ... open

User access Verification

Password:

R1>

We're in, and placed into user exec mode. Let's say we want to configure a new IP address on the ethernet interface on R1. We'll now go into privileged exec mode....

R1>enable

% No password set

R1>

.. or maybe we won't! The default behavior of Telnet on a Cisco router is to place the incoming user into user exec mode, and require an enable password to allow that user into privileged exec mode! right now, we can't configure anything on this router and even the show commands we would use are limited at best.

If we wanted to allow all telnetting users to be put into privileged exec mode immediately without being prompted for an enable password, the command privilege level 15 placed on the VTY lines will accomplish this.

R1(config)#line vty 0 4

R1(config-line)#privilege level 15

From R2, we'll telnet into R1 again.

R2#telnet 172.12.123.1

Trying 172.12.123.1 ... open

User access Verification

Password:

R1#

We were able to telnet in from R2 with the original password of "baseball", and even better, we were placed into privileged exec mode immediately!

You may or may not want to do this in real-world networks, though. If you want to assign privilege levels on an individual user basis, configure usernames and passwords and use the privilege 15 command in the actual username/password command itself to give this privilege levels to some users but not all.

R1(config)#username heidi password klum

R1(config)#username tim privilege 15 password gunn

Both users can telnet into the router, but the first user will be placed into user exec and challenged for the enable password to enter privileged exec mode. If there is no enable password, the user literally cannot get into privileged exec. The second user will be placed into privileged exec immediately after successfully authenticating.

Passwords on a Cisco router or switch are vitally important, and you're not tied down to granting "all-or-nothing" access. Knowing the details like the ones shown here help you tie down network security while allowing people to do their jobs - and it doesn't hurt to know this stuff for the CCNA exam, either!

Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage (http://www.thebryantadvantage.com).Good Music Yoga