13.3 Helpdesk: Understanding IP Addresses, Domain Names, and Protocols_sc

Domain Name

2. Within the top-level domains are many second-level domains. For example, in the .com top-level domain, there are many second-level domains such as Amazon.com, Google.com, and Microsoft.com.

TCP/IP Although many protocols are available on the Internet, the main suite of protocols used is TCP/IP. The suite is named after the original two protocols that were developed for the Internet

: the Transmission Control Protocol TCP) and the Internet Protocol IP). Although most people think that the TCP/IP suite consists of only two protocols, it actually comprises many interrelated protocols, the most important of which are shown here.

DHCP Dynamic Host Configuration Protocol)

A network service that provides automatic assignment of IP addresses and other TCP /IP configuration information.

IP address

A number assigned to any item that is connected to the Internet.

dynamic addressing

A way of assigning Internet protocol addresses where a computer is assigned a temporary address from an available pool of addresses.

What is an IP address and where I can find the IP address for my computer?

An IP address is a unique number identification assigned to each computer, server, or device connected to the Internet. To find your IP address, go to Google and type "what is my IP".

Packet Components

At a minimum, all packets must contain: 1. An address to where the packet is being sent, 2. Reassembling instructions if the original data was split between packets, and 3. The data that is being transmitted.

Dynamic Host Configuration Protocol DHCP) 2

Because dynamic IP addresses are always changing, your computer is less vulnerable to hacker attacks than with a static IP address.

When my friend connects to my computer, how is data transferred?

Computers communicate efficiently using the communication methodology called packet switching.

But how do computers get the IP address from a domain name?

Computers consult the domain name system (DNS) server. The DNS server contains a mapping of domain names with their corresponding IP addresses.

DNS

Domain Name System

Domain Name A domain name is simply a name that takes the place of an IP address, making it easier for people to remember it. Yahoo.com and AOL.com are domain names.

Domains are organized by level: 1. The portion of the domain name farthest to the right (after the dot) is the top-level domain (TLD). Examples of TLDs include .com, .edu, and .org.

Dynamic Host Configuration Protocol DHCP)

Dynamic addressing is normally handled by the dynamic host configuration protocol DHCP). When a user logs on to an ISP's server, the DHCP server assigns that user an IP address for the duration of the session. These temporary IP addresses may or may not be the same from session to session.

IP Address Basics

Each device connected to the Internet is required to have a unique number identifying it, called an IP address. A typical IP address is expressed as a series of numbers separated by decimal points as follows: 197.169.73.63 Expressing an IP address like this is called a dotted decimal number or dotted quad). Computers work with binary numbers internally. The same IP address in binary form would be: 11000000.10101000.00101000.00111111 The four parts in this notation are each referred to as an octet because each section has eight numbers.

Packet Transmission Sending a packet is like sending a letter. Say you are sending a very long letter to your aunt. The letter is too big to fit in one envelope, so you mail three envelopes.

Each one includes your aunt's address, a return address, and different pages of the letter. Each envelope may not find its way to San Diego by the same route, but they will all eventually arrive in your aunt's mailbox.

File Transfer Protocol (FTP)

Enables files to be downloaded to a computer or uploaded to other computers

Telnet

Enables user to login to a remote computer and work on it as if sitting in front of it

Domain Name Servers

How does your computer know the IP address of another computer? It uses a database maintained on a domain name system DNS), which functions like a phone book for the Internet.

Static and Dynamic addressing

IP addresses are either assigned statically or dynamically. When a computer has a static addressing, it means that the IP address never changes. Static IP addresses are most likely assigned manually by a network administrator. When a computer has a dynamic addressing, it means that your ISP assigns your computer a temporary IP address from an available pool of IP addresses each time you log on to the Internet.

Packet Switching

Occurs when the sending computer divides a message into a number of efficiently sized units called packets, each of which contains the address of the destination computer the transmission technology that divides blocks of text into packets

Finding Your IP Address

One way to find out your IP address is to go to Google and type "what's my IP". Google will show your IP address at the top of the search results.

Packet switching and Circuit Switching

Packet switching is the communications methodology that computers use to transfer data. It replaced circuit switching, the communications methodology used on devices like the telephone. In circuit switching, a dedicated connection is formed between two points (for example, between two people on telephones) and the connection remains active for the duration of the transmission. This method of communication is extremely important when communications must be received in the order in which they were sent (such as in telephone conversations). Packet switching does not require a dedicated communications circuit to be maintained. With packet switching, data is broken into smaller chunks (called packets or data packets) and sent over various routes at the same time. When the packets reach their destination, they are reassembled by the receiving computer.

How do packets travel through the Internet?

Packets are routed using Transmission Control Protocol/Internet Protocol (TCP/IP). TCP/IP is a suite of protocols used to route packets over the Internet.

Transmission Control Protocol (TCP)

Prepare data for transmission and provides for error checking and resending of lost data

User Datagram Protocol (UDP)

Prepares data for transmission; lacks resending capabilities

Internet Protocol (IP)

Sends data between computers on the Internet

Packets

Small chunks of information that have been carefully formed from larger chunks of information.

Dynamic Host Configuration Protocol (DHCP)

Takes a pool of IP addresses and shares them with hosts on a network on an as-needed basis

Does the IP address remain the same or can it change automatically?

The IP address changes automatically if your computer has a dynamic IP address. A dynamic IP address is a temporary IP address and is assigned by your ISP when your computer connects to the Internet.

Internet Protocol The Internet Protocol IP) is the protocol that is actually responsible for sending the information from one computer to another.

The IP is like a postal worker who takes a letter (a packet of information) that was mailed created by the sending computer) and sends it on to another post office, which in turn routes it to the addressee receiving computer).

What if the ISP's web server cannot locate the IP information on the default DNS server?

The default DNS server contacts one of the DNS servers. A root DNS server knows the location of all the DNS servers that contain the master listings for an entire top-level domain.

If data is broken into chunks and sent over various routes at the same time, how do these packets reach their destination?

The packets contain destination information and are reassembled when they all reach the destination.

static addressing

The process of assigning IP addresses by manually typing them into client computers.

Hypertext Transfer Protocol (HTTP) and HTTP secure (HTTPS)

Transfers Hypertext Markup Language (HTML) data from servers to browsers, HTTPS is an encrypted protocol for source transmissions

TCP/IP

Transmission Control Protocol/Internet Protocol

Simple Mail Transfer Protocol (SMTP)

Used for transmission of e-mail messages across the Internet

Is there an alternative to remembering IP addresses?

Yes, you can use a domain name. A domain name is simply a name that takes the place of an IP address, making it easier to remember.

Packet Transmission 2

Your aunt will then put the pages of the letters in order and read it. The process of sending a message through the Internet works in much the same way, as we see here.

Internet Protocol

a set of rules governing the format of data sent over the Internet or other network.