Isn't NAT a MUST when a LAN uses rfc 1918 private IPs?

Posted by aks on Server Fault See other posts from Server Fault or by aks
Published on 2010-04-07T15:53:11Z Indexed on 2010/04/07 16:03 UTC
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nat

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ipv4

Isn't NAT a MUST when a LAN uses rfc 1918 private IPs? Can an organization assign its hosts with private IPs and still communicate with the external world without NAT?

how can an internal host with a private IP (say 10.1.1.1) communicate with external world without NAT? I mean, how can the reply/response packet from the external world reach the original source as the packet with Dest IP = 10.1.1.1 will get lost as it can not be routed as many organizations can use the same IP.

Why doesn't rfc 1918 (Address Allocation for Private Internets) make any mention of NAT?

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