How to know your local gateway ip or details of nslookup command ?

Yesterday i was doing my work, and one of my colleague came to me and asked about the output of the nslookup command. So the question is very simple. He said me that when we do nslookup then what is the significance of server name and ip address that comes at top of the result.

>nslookup saketjain.com

Server:  UnKnown

Address:  10.10.10.1

 

Non-authoritative answer:

Name:    saketjain.com

Address:  68.168.100.135

 

What is this server name “Unknown” and which ip address 10.10.10.1 is this?

He said that he knows that the entry in non-authoritative answer tells us the ip address and domain name as well as cname entry of the server but he is not aware of the entry that comes above it.

So i showed him /etc/resolv.conf entry of the system which contains the same ip address and host name, and the answer is clear that this is the ip address of our local gateway/dns slave/master server through which our system queries for getting the ip address of the hostname or vice versa.

Now to understand this lets look at the output of ipconfig on my machine.

>ipconfig

Wireless LAN adapter Wireless Network Connection:

Connection-specific DNS Suffix  . : local

Link-local IPv6 Address . . . . . : fe80::a11a:df12:86a1:f6a1%10

IPv4 Address. . . . . . . . . . . : 10.10.10.32

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

Default Gateway . . . . . . . . . : 10.10.10.1

 

Now the answer is clear since we don’t have any dns slave/master server exists in our network, this is the gateway ip that helps our pc to reach the actual dns server and bring us the result. In linux, just see /etc/resolv.conf entry and in case your linux system is not abale to resolve any ip/hostname then you need to update entry in resolv.conf.

If you want to understand it better than just look at the output of tracert in windows and traceroute in linux and you will came to know how our system/network resolves a ip/hostname address.

 

For example:-

>tracert saketjain.com

Tracing route to saketjain.com [68.168.100.135]

over a maximum of 30 hops:

  1     2 ms     1 ms     1 ms  10.10.10.1

2     2 ms     2 ms     1 ms  192.168.1.1

3     6 ms     6 ms     7 ms  182.73.19.141

4    52 ms    53 ms    53 ms  125.21.167.29

5   168 ms   169 ms   168 ms  pos14-2.palermo6.pal.seabone.net [195.22.197.141

]

6   208 ms   208 ms   210 ms  xe-3-1-1.franco31.fra.seabone.net [195.22.211.10

7]

7   210 ms   209 ms   210 ms  xe-2-0-0.mpr1.fra4.de.above.net [64.125.13.49]

8   222 ms   222 ms   222 ms  xe-0-1-0.mpr2.cdg12.fr.above.net [64.125.24.94]

 

9   221 ms   221 ms   221 ms  xe-5-2-0.mpr1.lhr3.uk.above.net [64.125.24.81]

10   287 ms   304 ms   287 ms  xe-4-3-0.cr2.dca2.us.above.net [64.125.24.41]

11   317 ms   317 ms   402 ms  xe-2-2-0.cr2.iah1.us.above.net [64.125.30.53]

12   318 ms   333 ms   328 ms  xe-1-1-0.mpr4.phx2.us.above.net [64.125.30.149]

 

13   345 ms   335 ms   314 ms  xe-1-0-0.mpr3.phx2.us.above.net [64.125.27.97]

14   298 ms   298 ms   298 ms  64.125.192.194.t00738-01.above.net [64.125.192.1

94]

15   312 ms   311 ms   311 ms  gi4-18.cr1.phoenix.codero.com [69.64.66.17]

16   316 ms   314 ms   318 ms  gi1-45.dr1.dg2.phoenix.codero.com [69.64.66.30]

 

17   301 ms   300 ms   307 ms  unlimited.inwayhosting.com [68.168.100.135]

 

Trace complete.

>

So you can now see how our system finally resolved the actual ip address and hostname using these many gateways/dns slave/master servers in between.

Leave a Reply

Your email will not be published. Name and Email fields are required.


5 − = two

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>