What is an IP address?
What is an IP address? Very basic and simple explanation.

IP Address (Internet Protocol Address, IPv4 specification, IPv6 specification): This number is an exclusive number all information technology devices (printers, routers, modems, et al) use which identifies and allows them the ability to communicate with each other on a computer network. There is a standard of communication which is called an Internet Protocol standard (IP). In laymans terms it is the same as your home address. In order for you to receive snail mail at home the sending party must have your correct mailing address (IP address) in your town (network) or you do not receive bills, pizza coupons or your tax refund. The same is true for all equipment on the internet. Without this specific address, information cannot be received. IP addresses may either be assigned permanently for an Email server/Business server or a permanent home resident or temporarily, from a pool of available addresses (first come first serve) from your Internet Service Provider. A permanent number may not be available in all areas and may cost extra so be sure to ask your ISP.

Domain Name Server (DNS): This allows the IP address to be translated to words. It is much easier for us to remember a word than a series of numbers. The same is true for email addresses.

For example, it is much easier for you to remember a web address name such as some_host_name.com than it is to remember 10.1.1.1 or in the case of email it is much easier to remember anonymous@some_host_name.com than anonymous@10.1.1.1

Dynamic IP Address: An IP address that is not static and could change at any time. This IP address is issued to you from a pool of IP addresses allocated by your ISP or DHCP Server. This is for a large number of customers that do not require the same IP Address all the time for a variety of reasons. Your computer will automatically get this number as it logs on to the network and saves you the trouble of having to know details regarding the specific network configurations. This number can be assigned to anyone using a dial-up connection, Wireless and High Speed Internet connections. If you need to run your own email server or web server, it would be best to have a static IP.

Static IP Address: An IP address that is fixed and never changes. This is in contrast to a dynamic IP address which may change at any time. Most ISP's a single static IP or a block of static IP's for a few extra bucks a month.

IP version 4: Currently used by most network devices. However, with more and more computers accessing the internet, IPv4 addresses are running out quickly. Just like in a city, addresses have to be created for new neighborhoods but, if your neighborhood gets too large, you will have to come up with an entire new pool of addresses. IPv4 is limited to 4,294,967,296 addresses.

IP version 5: This is an experimental protocol for UNIX based systems. In keeping with standard UNIX (a computer Operating System) release conventions, all odd-numbered versions are considered experimental. It was never intended to be used by the general public.

IP version 6: The replacement for the aging IPv4. The estimated number of unique addresses for IPv6 is 340, 282, 366, 920, 938, 463, 463, 374, 607, 431, 768, 211, 456 or 2^128.

The old and current standard of addresses was this: 10.1.100.100 the new way can be written different ways but means the same and are all valid:

* 1080:0000:0000:0000:0000:0034:0000:417A

* 1080:0:0:0:0:34:0:417A

* 1080::34:0:417A

Short MEMO of basic IP address configuring and testing commands for UNIX, Windows, DOS, Linux
Windows/DOS Linux UNIX
Display Connection Configuration
ipconfig /all
Display DNS Cache Info Configuration
ipconfig /displaydns
Clear DNS Cache
ipconfig /flushdns
Release All IP Address Connections
ipconfig /release
Renew All IP Address Connections
ipconfig /renew
Re-Register the DNS connections
ipconfig /registerdns
Change/Modify DHCP Class ID
ipconfig /setclassid
Network Connections
control netconnections
Network Setup Wizard
netsetup.cpl
Test Connectivity
ping host.com
Trace IP address Route
tracert
Displays the TCP/IP protocol sessions
netstat
Display Local Route
route
Display Resolved MAC Addresses
arp
Display Name of Computer Currently on
hostname
Display DHCP Class Information
ipconfig /showclassid
Display Current Config for all NIC's
ifconfig
Display Current Config for eth0
ifconfig eth0
Assign IP
ifconfig eth0 10.1.1.1
Assign IP/Subnet
ifconfig eth0 10.1.1.1 netmask 255.0.0.0
Assign Default Gateway
route add default gw 10.1.1.1
Assign multiple IP's
ifconfig eth0:0 10.1.1.1
Assign second IP
ifconfig eth0:1 10.1.1.1
Disable network card
ifconfig eth0 down
Enable network card
ifconfig eth0 up
View current routing table
route "or" route -n
View arp cache
arp "or" arp -n
Ping
ping -c 3 host.com
Trace Route
traceroute host.com
Trace Path
tracepath host.com
DNS Test
host host.com
Advanced DNS Test
dig host.com
Reverse Lookup
host host.com
Advanced Reverse Lookup
dig -x 10.1.1.1
Display Current Config for all NIC's
ifconfig
Display Current Config for dc0
ifconfig dc0
Assign IP/Subnet
ifconfig dc0 inet 10.1.1.1 netmask 255.0.0.0
Assign Gateway
route delete default
route add default 10.1.1.1
Assign multiple IP's
ifconfig dc0:0 10.1.1.1
Assign second IP
ifconfig dc0:1 10.1.1.1
Disable network card
ifconfig dc0 down
Enable network card
ifconfig dc0 up

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