DNS NSLOOKUP

[kashyap1977]

hi

Ok now about this dynamic DNS, i just want to know that, from one of our desktop i am using nslookup.

What is this NSLOOKUP & when it is useful??

When i am issuing a command on nslookup like cisco.com it gives me the following output

> yahoo.com

Server: w-mum-dc2.3globalservices.com

Address: 172.27.1.142

Non-authoritative answer:

Name: yahoo.com

Addresses: 216.109.127.30, 66.218.71.198, 216.109.127.28, 216.109.127.29

what is this Public IP Address & what is the meaning of Non-authoritative answer.

kindly reply.

regards

kashyap

[myounger]

NSLOOKUP is troubleshooting tool used for DNS problems. The public addresses shown are the IP addresses assigned in DNS to this host.

[jamey]

Hello,

Non-autoritative answers are your 172.27.1.142 DNS server returning the yahoo.com IPs from it's cache. In other words, your 172.27.1.142 DNS server didn't have to go out on the Internet to resolve the domain name.

The reason you get all those IPs for yahoo.com is due to load-balancing. In this case, yahoo.com resolves to those 4 IP addresses. Your PC will typically pick the first one in the list if you were to go to access yahoo.com. If you were to do a lot of nslookups on yahoo.com you'll notice the 4 IPs rotate in the sequence they are in.

Like this:

> yahoo.com

Server: xxxxxxxxx

Address: x.x.x.x

Non-authoritative answer:

Name: yahoo.com

Addresses: 216.109.127.28, 216.109.127.29, 216.109.127.30, 66.218.71.198

> yahoo.com

Server: xxxxxxxxx

Address: x.x.x.x

Non-authoritative answer:

Name: yahoo.com

Addresses: 216.109.127.29, 216.109.127.30, 66.218.71.198, 216.109.127.28

>

Hope this helps you.