It is a dns server that i set up therefore this dns

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am recording. It is a DNS server that I set up, therefore this DNS server is not authoritative for the testout.com domain, meaning that it doesn't have any records configured for testout.com. Because it doesn't have any records configured for the testout.com domain, my DNS server here had to actually send a request to a root level DNS server out on the internet and say hey, can you give me the IP address of a host that is authoritative for the .com domain and the root level DNS server did that. Then my DNS server had to contact that server that's authoritative for .com and say hey, can you send me an IP address for a DNS server that's authoritative for the testout.com domain and that server did. At this point my DNS server now knows the IP address of the DNS server out on the internet that is authoritative for testout.com. It sends the request for a lookup of to that server.That server responds to my DNS server and then my DNS server responds to the nslookup command running on this workstation with the appropriate mapping and my DNS server, by the way, actually probably cached this mapping and will keep it. That way the next time it need to look up , it doesn't have to go through that whole process of contacting the root level server and then the .com authoritative server and then the testout.com authoritative server to resolve this hostname. Instead it says oh, you want . I happen to have that IP address cached here locally. I'll just send it to you directlywithout talking to those other servers. Okay, so that's how you use nslookup in non-interactive mode. Interactive Mode 4:26-5:41 Now let's talk about how you use nslookup in interactive mode. In interactive mode we simply type nslookup without providing a hostname to resolve and just press Enter. Notice when I do, that it tells me which server it's going to be communicating with to resolve hostnames and it provides a little prompt here that I can submit one hostname after another for name resolution. For example, I can do . It provides me with a name resolution. Now instead of having type the command again, I just type the next DNS name that I want to resolve such as , and once again it provides me with the IP address or this hostname and you can just keep on going for as long as you want. and here's the IP address for . When you're done, you just simply type 'exit' and it takes you out of interactive mode with nslookup.Now before we end I want to point out that nslookup is actually capable of performing much more advanced name resolution requests than those we looked at here. If you want more details on how you can use nslookup, type 'nslookup /?'. Summary 5:42-5:46 That's it for this demonstration. In this demo, we talked about how to use the nslookup command to test your name resolution system.
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