Programming Reflection: How to find IP Address from hostname in Windows Linux and Unix

IP Address from hostname in Windows and Linux
How many times in a day you have a hostname and you want to know the IP address? Host name to IP address and IP address to hostname conversion is one of frequent thing which we need to do for many things when dealing with networking command in unix. For one command we need IP address for other we need hostname even from bash script some time we require hostname and some time we look for IP address. networking commands are not as popular as find command or grep command but they are equally important and if you working in Windows or UNIX environment you must learn them and they should also be included in any list of Unix commands for beginners. By the way In this hostname to IP address tutorial I will show you how to get IP address from hostname or computer-name in Unix or Linux and how to get hostname if you have IP address. If you are looking a way to do it via Java program then you can also see my post how to find IP address of localhost in Java.

Finding IP address from hostname in UNIX and Linux

If you are working in UNIX network and have lots of machine in LAN (Local Area network), many times you want to know IP address of computers from hostname. Here are top 4 ways of getting IP address from hostname in Linux or UNIX machine

1) IP address using hostname command in Unix/Linux

This is the easiest way of finding IP address of your computer but limitation is that sometime this option may or may not available in your UNIX machine e.g. I hardly find this command on Solaris and IBM AIX machines but they are mostly available on Linux Servers. also limitation of hostname is that you can not find IP address of any other machine. It's like finding IP address of localhost.

2) IP address using ping command in UNIX or Linux

stock_trader@system:~/test ping trading_system

Pinging trading_system.com [192.24.112.23] with 32 bytes of data:

Reply from 192.24.112.23: bytes=32 time<1ms TTL=128

ping is another simplest way of finding IP address of localhost or any other host in network, if you know the hostname or computer-name just ping and it will display IP address associated with it. Normally pint command is used to check if a host is alive and connected with network. In above example IP address associated with trading_system is "192.24.112.23". Disadvantage of using ping command is that you can not convert IP address back to hostname.

3) IP address using nslookup command in UNIX or Linux

stock_trader@system:~/test nslookup trading_system

Name: trading_system.com

Address: 192.24.112.23

nslookup is my favorite command for getting IP address form hostname, its very powerful and also available in many UNIX operating system e.g. Linux , Solaris, IBM AIX, Ubuntu or BSD. Another advantage of nslookup command is that , we can get either from hostname to IP address or from IP address to hostname. It can also be used to find IP address of your own host or any other machine in the network. In above example of nslookup we have displayed IP address associated with trading_system. If you want to find hostname form IP address you can just provide IP address instead of hostname

4) How to find IP address using ifconfig command

ifconfig is another networking utility in UNIX or Linux which can be used to find IP address of your UNIX machine. ifconfig shows lot of information so I just grep on inet to find the IP address in below example, IP address associate with "trading_system.com" is "192.24.112.23".

trading_system.com $ /sbin/ifconfig -a | grep inet

inet 192.24.112.23 netmask ffffff00 broadcast 192.24.112.255

IP Address from hostname in Windows Linux and Unix

How to find IP address of your computer in Windows

Surprisingly some of above example of finding IP address from hostname will work is windows ditto. You can use ping and nslookup in exactly same way as shown above. Even hostname command is available in windows command prompt but I doubt about options "hostname -i". Another change is in command ifconfig , instead of ifconfig windows uses ipconfig command to find out the IP address of your computer in windows.

1) How of use ipconfig command in windows to find IP address

Here is an example of using ipconfig command in windows to find out IP address of our computer:

C:\Documents and Settings\stock_trader>ipconfig

Windows IP Configuration

Ethernet adapter Local Area Connection:

Connection-specific DNS Suffix . : trading_system.com

IP Address. . . . . . . . . . . . : 192.24.112.23

Subnet Mask . . . . . . . . . . . : 255.255.255.0

Default Gateway . . . . . . . . . : 192.24.112.254

How to find external IP address of your network or computer

All above example will show your internal IP address if you are inside a LAN. If you have connected with internet and want to know your external IP address assigned by your service provider there are lots of website which will let you know your IP address e.g. ipchicken.com just logging into this site and it will show you your IP address and location. If you have an IP address and wanted to know about location you can also get it from internet.

That’s it from me on these nice little tips of converting IP address to hostname and than back from hostname to IP address. Let me know if you have some other ways to find IP address and hostname of local machine and remote machine.

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