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The two most commonly used Unix commands for querying the Domain Name
Service system (they are not always both present on any particular Unix
system) are:
- host-- which provides output such as this:
- host ns1.umd.edu
ns1.umd.edu has address 128.8.74.2
host 128.8.74.2
Name: ns1.umd.edu
Address: 128.8.74.2
Aliases:
If you get a Host not found or Host not found, try again message,
either you misspelled the name or the name doesn't exist (or, if you specified an IP
address, it may just be that the information for converting from IP to name simply
hasn't been put into that domain's DNS).
- nslookup-- which provides output such as this:
- nslookup ns1.umd.edu
Server: the Unix machine you're using
Address: its IP address
Non-authoritative answer:
Name: ns1.umd.edu
Address: 128.8.74.2
- nslookup 128.8.74.2
Server: the Unix machine you're using
Address: its IP address
Name: ns1.umd.edu
Address: 128.8.74.2
The "Non-authoritative answer" message comes when your local DNS has already recently
looked up the item and is reporting back directly based on what it has in its cache
(storage of recent items), rather than going out to the DNS that is authorized to
handle the domain in question.
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