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I am trying to understand this:
When I set up my internet connection, I have to enter my ISP's IP address and possibly a DNS server address. In both those options I can enter either an actual IP address or an address such as cable.myISP.net or ns1.myISP.net.
My question is how can a domain name for a DNS server ever be resolved if I don't have a DNS server set up yet? And how can anything, IP or domain name, for my ISP work if I don't have a connection to anything?

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migrated from serverfault.com Nov 4 '10 at 9:04

This question came from our site for professional system and network administrators.

    
you actually get those settings from your ISP... give them a call... :) –  Owen Nov 4 '10 at 9:54
    
Actually you can use any dns servers you wish, they do not have to be from your isp, I use these Open DNS servers (208.67.222.222) (208.67.220.220). You need more detail in your question to get a specific answer to your question or problem. –  Moab Nov 4 '10 at 14:50
    
you're using your ISP's DNS server. Out of interest, where are you entering that data? I haven't heard of entering your ISP's IP address.. –  barlop Jun 16 '11 at 12:53

2 Answers 2

enter my ISP's IP address and possibly a DNS server address.

I assume we are talking about PPP or cable internet connection here. When your ISP telly you to enter a DNS server address, it means that the Domain Name (like www.google.com ) will be resolved to a IP address (in numbers, like 66.249.89.104) by that server. It is like a lookup table (very simplified). Of course, the DNS server can be anything, as long as the DNS server is reachable (by whatever IP address it has).

how can a domain name for a DNS server ever be resolved

This is where Dynamic Host Configuration Protocol (DHCP) comes into play. Your ISP has normally set up DHCP, so when your computer connects first time, it sends out a 'Hello? Any one there?' signal, and the ISP's DHCP server will respond with 'YEA, I'm here, and my IP address is XX.XX.XX.XX , and I dictate your IP address as YY.YY.YY.YY , so use it, ok, no more yelling, now go hush!', and the computer knows where to look for. DHCP can provide many more things, not just IP and DNS server address, but that is off topic so I will leave it here...

Reading: Domain_Name_System , DHCP

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You do have to identify your primary DNS server by it's IP-address. If you run a local DNS server (such as BIND) it does however come preconfigured with "root hints" that provide sufficient information for it to find other Internet DNS nameservers.

If you really don't have a connection to anything then you can't contact anything. This is obvious, so this part of your question is unclear. Perhaps you could clarify it.

Networking software is layered, you only need a connection at the lowest level (Ethernet, ADSL) to be able to set up and use the next layer of network services (IP then DNS, HTTP, ...)

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