Internet Surface

Internet world is similar to our Universe like bright side and the dark side. In Internet system there is also two side one is surface web and another one is  deep web. Whatever i write in this page the reader can read this for knowledge only and I am not responsible for affecting or inciting anyone.

Surface Web : In this web which is visible and accessible for every one it is legal web. You can search any kind of web sites on google and google shows only visible and accessible web site which known as Surface Web. It has static and crawl-able web pages. In this web surface large amount unfiltered information. what is easily found by search engines is limited.
Deep Web : In this web which is invisible or hidden for security reason or password protected contents are stored in this web. It is also legal but some secret agency, banking and government authorized sectors can share their information through deep web that is why it is hidden. The deep web has long been blamed for the globalization of cyber-crime. In recent years, malicious and illegal commercial activities in dark net market are increasingly becoming common in many countries around the world. This has led to these platforms and their participants coming under increased pressure from authorities but that happened in Dark Web which is also the part of deep web. In dark web all illegal activity happened so it is very risky and harmful for others. If you want to access Deep Web you need to install Tor Browser. In surface web there sites like .com, .org etc. but In deep web sites like .onion.

Transmission Media

Coaxial Cables : It is used by cable operators but sometimes ago it also used by telephone companies. Coaxial cable is a type of cable that has an inner conductor surrounded by an insulating layer, surrounded by a conductive shielding. Many also have an insulating outer jacket The diagram below illustrates the construction of a typical cable. Electrical signal flows through the center conductor.

Table. Common coaxial cable types and uses. There are many additional RG designations, as well as variations within each number class.

Cable type	Ω	Use
RG-6	75	Video, TV
RG-8	50	Radio, computer
RG-11	75	Long runs
RG-58	50	Radio, computer
RG-59	75	Video, TV

Advantages : 

1. Coaxial cable can support greater cable lengths between network devices than twisted pair cable.

2. Thick coaxial cable has an extra protective plastic cover that help keep moisture away and stronger.

Disadvantages :

1. Thick coaxial is not bend easily so, it is difficult to install.

2. Difficult to troubleshoot a simple issue.

Twisted Pair Cables : Twisted pair cable consists of a pair of insulated wires twisted together. It is a cable type used in telecommunication for very long time. Cable twisting helps to reduce noise pickup from outside sources and cross-talk on multi-pair cables.

The most commonly used form of twisted pair is unshielded twisted pair (UTP). It is just two insulated wires twisted together. any data communication cables and normal telephone cables are this type. Shielded twisted pair(STP) differs from UTP in that it has a foil jacket that helps prevent cross-talk and noise from outside source. In data communications there is a cable type called FTP (foil shielded pairs) which consists of four twisted pair inside one common shield (made of aluminum foil). The following are the cable types specified in ANSI/TIA/EIA which are mention below:

Category 1 : Cat 1 cable was originally designed for voice telephony only, but thanks to some new techniques, long-range Ethernet and DSL, operating at 10Mbps and even faster, can be deployed over Cat 1.

Category 2 : Cat 2 cable can accommodate up to 4Mbps and is associated with token-ring LANs.

Category 3 : Cat 3 cable operates over a bandwidth of 16MHz on UTP and supports up to 10Mbps over a range of 330 feet (100 m). Key LAN applications include 10Mbps Ethernet and 4Mbps token-ring LANs.

Category 4 : Cat 4 cable operates over a bandwidth of 20MHz on UTP and can carry up to 16Mbps over a range of 330 feet (100 m). The key LAN application is 16Mbps token ring.

Category 5 : Cat 5 cable operates over a bandwidth of 100MHz on UTP and can handle up to 100Mbps over a range of 330 feet (100m). Cat 5 cable is typically used for Ethernet networks running at 10Mbps or 100Mbps. Key LAN applications include 100BASE-TX, ATM, CDDI, and 1000BASE-T. It is no longer supported, having been replaced by Cat 5e.

Category 5e : Cat 5e (enhanced) operates over a bandwidth of 100MHz on UTP, with a range of 330 feet (100 m). The key LAN application is 1000BASE-T. The Cat 5e standard is largely the same as Category 5, except that it is made to somewhat more stringent standards. Category 5e is recommended for all new installations and was designed for transmission speeds of up to 1Gbps (Gigabit Ethernet). Although Cat 5e can support Gigabit Ethernet, it is not currently certified to do so.

Category 6 : Cat 6, specified under ANSI/TIA/EIA-568-B.2-1, operates over a bandwidth of up to 400MHz and supports up to 1Gbps over a range of 330 feet (100 m). It is a cable standard for Gigabit Ethernet and other network protocols that is backward compatible with the Cat 5/5e and Cat 3 cable standards. Cat 6 features more stringent specifications for crosstalk and system noise. Cat 6 is suitable for 10BASE-T/100BASE-TX and 1000BASE-T (Gigabit Ethernet) connections.

Category 7 : Cat 7 is specified in the frequency range of 1MHz to 600MHz. ISO/IEC11801:2002 Category 7/Class F is a cable is based on four twisted copper pairs, features even more stringent specifications for crosstalk and system noise than Cat 6. 
Advantages : 
1. Cheaper and far easier to splice
2. Less susceptible to electrical interference caused by nearby equipment or wires.
3. In turn are less likely to cause interference themselves.
4. Because it is electrically "cleaner", STP wire can carry data at a faster speed.
Disadvantages : 
1. STP wire is that it is physically larger and more expensive than twisted pair
wire.
2. STP is more difficult to connect to a terminating block.

Fiber Optics or Optical fiber Cable :  
A fiber optic cable is a network cable that contains strands of glass fibers inside an insulated casing. They're designed for long distance, very high performance data networking and telecommunications.
Compared to wired cables, fiber optic cables provide higher bandwidth and can transmit data over longer distances. Fiber optic cables support much of the world's internet, cable television and telephone systems.
Advantages :
1. One single mode fiber can replace a metal of time larger and heavier.
2. Multi-mode optical cable has a larger diameter and can be used to carry signal
over short distance.
Disadvantages :
1. Fiber optic versus metal cable is that it is difficult to make connections to
fiber optic cable.
2. The optical fiber must be highly polished to allow light to pass with little loss. 

Network

Concept of Networking

Networking : The concept of networking is pretty simple. A couple of computers have some cables strung between them, and send data back and both using electrical signalling over the cable. More or less the same as telephones do or, in a very rough sense, like two kids speaking into tin cans connected by a string.
In simple way networking means two or more device can communicate with each other and sharing their respective information with the help of any kind of transmission media (wired or wireless).

Wired : In this scenario you can see that all device are connected with wired transmission media which known as Cable. In wired network, every desktop computer or device should be affixed to another desktop computers or a main appliance using cables.

Wireless : In this scenario all device connected with wireless media there is no using of any kind of cable. In other words wireless is the term used to describe any computer network where there is no physical wired connection between sender and receiver, but rather the network is connected by radio waves and/or microwaves to maintain communications.

 Types of Networks

LAN (Local Area Network) : It is a relatively small network covering small areas like a room, an office, a building, a campus etc. If you connect two computers for sharing data, you have a LAN. The number of computers connected on a LAN may be up to several hundreds, but most of the time, LANs are made up of more or less a dozen machines, as the idea behind a LAN is to cover a small area. The diameter of LANs can range from 100 meters to 1 kilometers.


MAN (Metropolitan Area Network) : It is a large computer network on the large geographical area that include several buildings or even the entire city (metropolis). The geographical area of the MAN is larger than LAN, but smaller than WAN. MAN includes many communicating devices and provides the Internet connectivity for the LANs in the metropolitan area.
MAN is used to combine into a network group located in different buildings into a single network. The diameter of such a network can range from 2 to 50 kilometers.

WAN (Wide Area Network) : It is a network that exists over a large-scale geographical area. A WAN connects different smaller networks, including local area networks (LANs) and metro area networks (MANs). This ensures that computers and users in one location can communicate with computers and users in other locations. WAN implementation can be done either with the help of the public transmission system or a private network. The diameter of WANs can range more than 50 kilometers

Network