How a router determines which DNS addresses to use?

Arwins Singh

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Oct 2, 2013
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I can't seem to understand the concept of how my router(with built in DHCP) knows the ip addresses of my ISP. Does the ISP use DHCP that hands out DNS server addresses to my router at home? and if so which device sends the broadcast signal first to the other?
 

namdlo

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Jun 20, 2012
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Typically your router isn't giving out external addresses. It's giving out internal addresses for your network.

The only time an external address is used is for the gateway of your router.

I'm willing go guess that your PCs are using either a 192.X.X.X or 10.X.X.X address - these are private not public.
 

Arwins Singh

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Oct 2, 2013
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Hey thanks for the reply Namdlo, I think you misunderstood what i'm asking. Yes I have my DHCP(on my router) configured to hand out a specific range of addresses to my private network. My question is when a router(with DHCP) is installed into a home network. How does it communicate with the ISP, to retrieve info such as DNS addresses? does it use the RIP protocol, and if so which device ( my router or whichever device the ISP is using ) initiates the communication first?


 

USAFRet

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It gets that from the Modem. Sometimes the modem and router are in the same physical box.

What does this router connect to?
 

Arwins Singh

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So your saying the modem is preconfigured to provide DNS information to my router? That must mean that the ISP's DNS ip addresses remain the same forever? My router(with DHCP and is a WAP) has a bridge(WAP) connected to it, and my home FTPS server, just for experimenting and troubleshooting.



 

Arwins Singh

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Does the Modem contact the ISP's DHCP server to get the info?