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General IP routing question

Posted on 2004-04-02
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Firstly apologies if this is not the right group for this question but maybe someone can point me in the right direction.

My question is:

say for example and ISP assigns a static IP say 214.92.183.18 and I assign this to my mail server. Can somebody explain how mail is routed to me and why mail would not be routed to somebody somewhere else who assigns 214.92.183.18 to their router.

I understand the process of DNS and how a packet is routed to my ISP name server but how is my ISP nameserver aware of the MAC address of my router in order to route the packet to me?

Thanks in advance
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Question by:Curnies
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by:liddler
liddler earned 75 total points
ID: 10739725
Your ISP will "own" the 214.92.183.0 network, so any packets destined for a machine in that network, will go to your ISP.  Their IP allocation scheme, whether manual or automatic should be designed to prevent duplication.
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by:stevenlewis
stevenlewis earned 150 total points
ID: 10739754
>>Can somebody explain how mail is routed to me and why mail would not be routed to somebody somewhere else who assigns 214.92.183.18 to their router
shouldn't happen, since you will get a conflict if more than one is assigned the ip address, they must be individual.
then dns and mx records take over
more info
http://www.rscott.org/dns/mx.html
http://www.han.com/dns.html
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by:Curnies
ID: 10739962
Thanks for the replies.

One question though. Say my connection is dialup isdn. What is there to prevent somebody else assinging my address to their router while my connection is down? There is no conflict in this case

More specifically I want to understand if the ISP routers maps traffic destined for my IP to the MAC address of my router what happens if my router crashes and has to be replaced - obviously the MAC address will change so how will DNS know that the new router with the new MAC is actually me?
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by:liddler
ID: 10740073
IF your ISP uses youe MAC address, you would have to tell them if you changed hardware.
Anyway if your ISP assigns you a static, they wouldn't let anyone else use it.  Usually on dial up, an ISP uses cli (Caller Line Identifier) and maps the IP to your telephone number.
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by:
Chatable earned 150 total points
ID: 10740770
Your ISP assigns IP addresses to its customers. If you have a static IP it means that your ISP has reserved that IP for you only. ISPs have many ways of identifying users, but if it's a dial-up then your identification is probably the username/password you type before connecting. When you successfully log-on using your username, the ISP will assign you the IP address that has been reserved to you.
Another thing - one mistake you've had: A MAC address is the one address that NEVER changes. It's burned into the circuitry of your Network Card (That's why it's called the Hardware Address). In addition, Dialup connections use the PPP protocol, which doesn't use MAC at all, so this discussion is somehow irrelevant.
Hope you better understand now.
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