FAQs ANSWERD

What is DNS?
Domain Name System (DNS) is an Internet Engineering Task Force (IETF) standard name service that allows your computer to register and resolve domain names.
The DNS makes it possible to assign domain names to organizations independent of the routing of the numerical IP address. In other words, DNS is a system that translates domain names into IP addresses. This is necessary because computers only make use of IP addresses yet we use only human readable names since the names are easier to remember than IP addresses.

What are the Seven layers of OSI(Open System Interconnection)Model?
Layer      Name
7      Application
6      Presentation
5      Session
4      Transport
3      Network
2      Data Link
1      Physical

What is Client/Server Networking?
The term client/server refers to a model utilizing networked client and server computers and application software. Web, FTP, email, DNS and many other database applications are client-server systems.

What is Peer-to-Peer Networking?
Peer to peer networks share responsibility for processing data among all of the connected devices. Peer-to-peer networking (also known simply as peer networking) differs from client-server networking in several respects.

What Is a Network Name?
A network name is a string that computing devices use to identify a specific computer network. Network names are typically different from names of individual computers or the addresses computers use to identify each other.

What Is URL?
URLs (Uniform Resource Locators) identify by name Web servers and individual Web pages stored on those servers, anywhere on the Internet.

What Is URI?
A URI (Uniform Resource Identifier) names both local and remote Internet resources similar to URLs.

What Is TCP?
TCP (Transmission Control Protocol) is the main transport protocol utilized in IP networks.
The TCP protocol exists on the Transport Layer of the OSI Model. The TCP protocol is a connection-oriented protocol which provides end-to-end reliability.
By connection-oriented, we mean that before two network nodes can communicate using TCP, they must first complete a handshaking protocol to create a connection.
When we say that TCP provides end-to-end reliability, we mean that TCP includes mechanisms for error detection and error correction between the source and the destination.
These properties of TCP are in contrast to UDP, which is connectionless and unreliable.Higher layer protocols which utilize TCP include HTTP, SMTP, NNTP, FTP, telnet, SSH, and LDAP.

Diagram of the TCP Header

                        TCP Header Format
                        -----------------

 0                   1                   2                   3
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|          Source Port          |       Destination Port        |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                        Sequence Number                        |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                    Acknowledgment Number                      |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|  Data |           |U|A|P|R|S|F|                               |
| Offset| Reserved  |R|C|S|S|Y|I|            Window             |
|       |           |G|K|H|T|N|N|                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|           Checksum            |         Urgent Pointer        |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                    Options                    |    Padding    |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                             data                              |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

What Is UDP?
User Datagram Protocol or UDP is part of the Internet Protocol suite, using which, programs running on different computers on a network can send short messages known as Datagrams to one another. UDP can be used in networks where TCP is traditionally used, but unlike TCP, it does not guarantee reliability or the right sequencing of data. Datagrams may go missing without notice, or arrive in a different order from the one in which they were sent.

What Is Dynamic DNS?
Dynamic DNS is a technology that allows you to update the IP address of a domain in real time. In order to fully understand how Dynamic DNS works, it is important to first understand domain names and name servers. Essentially, all website domain names are held on computer servers known as name servers. These servers are used, with the help of a Domain Name System (DNS) server, to change the domain name into something more easily recognizable by a computer, an Internet Protocol (IP) Address.

Who/What is Internet Engineering Task Force (IETF)?
The Internet Engineering Task Force (IETF) develops and promotes Internet standards, cooperating closely with the W3C and ISO/IEC standard bodies and dealing in particular with standards of the TCP/IP and Internet protocol suite. It is an open standards organization, with no formal membership or membership requirements. All participants and managers are volunteers, though their work is usually funded by their employers or sponsors; for instance, the current chairperson is funded by VeriSign and the U.S. government's National Security Agency.

What are LAN and WAN?
A local area network (LAN) is a group of computers and associated devices that share a common communications line or wireless link. Typically, connected devices share the resources of a single processor or server within a small geographic area (for example, within an office building). Usually, the server has applications and data storage that are shared in common by multiple computer users. A local area network may serve as few as two or three users (for example, in a home network) or as many as thousands of users.


Wide Area Network (WAN) is a computer network that covers a broad area (i.e., any network whose communications links cross metropolitan, regional, or national boundaries). This is in contrast with personal area networks (PANs), local area networks (LANs), campus area networks (CANs), or metropolitan area networks (MANs) which are usually limited to a room, building, campus or specific metropolitan area (e.g., a city) respectively. The largest and most well-known example of a WAN is the Internet. WANs are used to connect LANs and other types of networks together, so that users and computers in one location can communicate with users and computers in other locations. Many WANs are built for one particular organization and are private. Others, built by Internet service providers, provide connections from an organization's LAN to the Internet. WANs are often built using leased lines. At each end of the leased line, a router connects to the LAN on one side and a hub within the WAN on the other. Leased lines can be very expensive. Instead of using leased lines, WANs can also be built using less costly circuit switching or packet switching methods. Network protocols including TCP/IP deliver transport and addressing functions. Protocols including Packet over SONET/SDH, MPLS, ATM and Frame relay are often used by service providers to deliver the links that are used in WANs. X.25 was an important early WAN protocol, and is often considered to be the "grandfather" of Frame Relay as many of the underlying protocols and functions of X.25 are still in use today (with upgrades) by Frame Relay.

What is Intrusion Detection System? or IDS
IDS means Intrusion detection system, is software and/or hardware designed to detect unwanted attempts at accessing, manipulating, and/or disabling of computer systems, mainly through a network, such as the Internet. These attempts may take the form of attacks, as examples, by crackers, malware and/or disgruntled employees. An IDS cannot directly detect attacks within properly encrypted traffic.An intrusion detection system is used to detect several types of malicious behaviors that can compromise the security and trust of a computer system. This includes network attacks against vulnerable services, data driven attacks on applications, host based attacks such as privilege escalation, unauthorized logins and access to sensitive files, and malware ("viruses, trojan horses, and worms).
An IDS can be composed of several components: Sensors which generate security events, a Console to monitor events and alerts and control the sensors, and a central Engine that records events logged by the sensors in a database and uses a system of rules to generate alerts from security events received. There are several ways to categorize an IDS depending on the type and location of the sensors and the methodology used by the engine to generate alerts. In many simple IDS implementations all three components are combined in a single device or appliance.http://en.wikipedia.org/wiki/Intrusion_detection_system

Software is considered malware based on the perceived intent of the creator rather than any particular features. Malware includes computer viruses, worms, trojan horses, most rootkits, spyware, dishonest adware, crimeware and other malicious and unwanted software. In law, malware is sometimes known as a computer contaminant, for instance in the legal codes of several U. S. states, including California and West Virginia.

What are Computer Worms?
A computer worm is a self-replicating computer program. It uses a network to send copies of itself to other nodes (computers on the network) and it may do so without any user intervention. Unlike a virus, it does not need to attach itself to an existing program. Worms almost always cause at least some harm to the network, if only by consuming bandwidth, whereas viruses almost always corrupt or devour files on a targeted computer.

What Is Network layer?

The network layer attempts to deliver packets from a node on one network segment to another node that may be on another network segment. All network layer protocols use a header that includes both a source and destination address. Network layer addresses consist of two parts: A network segment prefix which identifies the network segment and a node suffix, which identifies the node on the segment.

An IP version 4 address is a total of 32 bits. The division of bits between the network segment prefix and the node varies. The network segment prefix is divided into 2 parts: The network number which is unique in the world and a subnet number with is assigned at the campus level.

An IPX address is a total of 80 bits. 32 bits is used for the network number and 48 bits is used for the node number. In most cases the node number is the Ethernet address. Since we do not participate in a global IPX network, the network number is assigned at the campus level. The convention for IPX network numbers on the Madison campus is that the IPX network number is an IP address on the same network segment.

An Appletalk address is a total of 24 bits. 16 bits are used for the network number and 8 bits for the node number. The node number is chosen automatically at random from the node numbers that are not in use at the time the node starts up, so the node number may vary across startups.

The network layer does not guarantee delivery of packets. Packets may be dropped due to transmission errors, network congestion, an unknown address, or other reasons.

What is IP Address Spoofing?
IP address spoofing means generating IP packets/ data with fake IP addresses.

What Is Client/Server Architecture
A Client/Server Architecture also known as Network architecture, where Each System / Computer / Process on the network is known as either a client or a Server.
Servers are more powerful than the clent systems they manage disk drives (file servers), printers (print servers), or network traffic (network servers ).
Clents are known as PCs or Workstations on which users run applications.Clients rely on servers for resources, such as files, devices, and even processing power.
Another type of network architecture is known as a peer-to-peer architecture because each node has equivalent responsibilities. Both client/server and peer-to-peer architectures are widely used, and each has unique advantages and disadvantages. Client-server architectures are sometimes called two-tier architectures.

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