Browsers, mail clients, ftp and ssh and telnet clients and the rest are for ever converting fully qualified names such as www.sheepbingo.co.uk into IP addresses such as 212.227.118.78. How can you do such a lookup manually?

Firstly, there are numerous web sites out there that will help you - I'm not supplying any links here because I'm sure you already have your own favourite. But did you know that there are ... not one ... not two ... but three utilities under Linux to do the job for you?

The host command does a quick and dirty lookup:

[trainee@saturday trainee]$ host www.sheepbingo.co.uk
www.sheepbingo.co.uk has address 212.227.118.78
[trainee@saturday trainee]$

The dig command tells you a lot more:

[trainee@saturday trainee]$ dig www.sheepbingo.co.uk

; <<>> DiG 9.2.1 <<>> www.sheepbingo.co.uk
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<<- opcode: QUERY, status: NOERROR, id: 31254
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;www.sheepbingo.co.uk. IN A

;; ANSWER SECTION:
www.sheepbingo.co.uk. 10476 IN A 212.227.118.78

;; Query time: 17 msec
;; SERVER: 158.152.1.43#53(158.152.1.43)
;; WHEN: Wed Jun 1 08:42:54 2005
;; MSG SIZE rcvd: 54

[trainee@saturday trainee]$

And the deprecated nslookup give interactive facilites too

[trainee@saturday trainee]$ nslookup www.sheepbingo.co.uk
Note: nslookup is deprecated and may be removed from future releases.
Consider using the `dig' or `host' programs instead. Run nslookup with
the `-sil[ent]' option to prevent this message from appearing.
Server: 158.152.1.43
Address: 158.152.1.43#53

Non-authoritative answer:
Name: www.sheepbingo.co.uk
Address: 212.227.118.78

[trainee@saturday trainee]$

(written 2005-06-01, updated 2010-10-26)

 A163 - Web Application Deployment - Network Configuration and Security
  [3448] Checking all the systems on a subnet, using Expect and Tk - (2011-09-18)
  [2489] Parallel Pinging, using Python Threads or Expect spawn lists - (2009-11-02)
  [2052] How was my web site compromised? - (2009-02-24)
  [1904] Ruby, Perl, Linux, MySQL - some training notes - (2008-11-23)
  [1712] As different as night and tyres - (2008-07-18)
  [1666] Slow boot and terminal start on Linux boxes - (2008-06-05)
  [1408] Wireless hotel tips - FTP and Skype connections failing - (2007-10-26)
  [1073] Heartbeat script in Perl - (2007-02-09)
  [511] Domain Forwarding - 2 ways of doing it - (2005-11-29)
  [506] What are DHCP and DNS? - (2005-11-27)
  [267] Searching security holes - (2005-04-04)
  [37] Security and Safety - (2004-09-03)
  [11] A bolt of lightning on Multicasting - (2004-08-11)

W501 - Introduction to Web Site Structure
  [2552] Web site traffic - real users, or just noise? - (2009-12-26)
  [2282] Checking robots.txt from Python - (2009-07-12)
  [2214] Global Index to help you find resources - (2009-06-01)
  [2094] If you have a spelling mistake in your URL / page name - (2009-03-21)
  [1969] Search Engines. Getting the right pages seen. - (2009-01-01)
  [1686] FTP - how not to corrupt data (binary v ascii) - (2008-06-24)
  [1636] What to do if the Home Page is missing - (2008-05-08)
  [1431] Getting the community on line - some basics - (2007-11-13)
  [1198] From Web to Web 2 - (2007-05-21)
  [1176] A pu that got me into trouble - (2007-05-04)
  [1168] Moving out some of the web site bloat - (2007-04-29)
  [1031] robots.txt - a clue to hidden pages? - (2007-01-13)
  [1024] Web site - a refresh to improve navigation - (2007-01-07)
  [528] Getting favicon to work - avoiding common pitfalls - (2005-12-14)

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