如何获取DNS名称服务器的IP地址

Question

When I do an nslookup on the net. zone, I get the following output:

nslookup -type=soa net 8.8.8.8
Server:     8.8.8.8
Address:    8.8.8.8#53

Non-authoritative answer:
net
    origin = a.gtld-servers.net
    mail addr = nstld.verisign-grs.com
    serial = 1542217316
    refresh = 1800
    retry = 900
    expire = 604800
    minimum = 86400

Authoritative answers can be found from:

This means that in order to get DNS records for the net. zone, one should query the DNS Server a.gtld-servers.net. However, the IP Address of a.gtld-servers.net is not given. This results in a catch-22, because in order to get the IP address of any subzone in the net. zone, one should query a.gtld-servers.net.

So my question is, how to get out of this catch-22? How can I get the IP address of a.gtld-servers.net without having to do another DNS request?

Answer 1

The root server addresses can be found in a file downloaded from iana

This means that in order to get DNS records for the net. zone, one should query the DNS Server a.gtld-servers.net

You could, and at least initially, probably would, but the root servers don't move around frequently, so once you got the ip address for .net server, for example, you would use the cached value.