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Chapter 11 NAT
11.3 Technical Reference
The following section contains additional technical information about the features described in this
chapter.
NAT Loopback
Suppose a NAT 1:1 rule maps a public IP address to the private IP address of a LAN SMTP e-mail
server to give WAN users access. NAT loopback allows other users to also use the rule's original IP
to access the mail server.
For example, a LAN user's computer at IP address 192.168.1.89 queries a public DNS server to
resolve the SMTP server's domain name (xxx.LAN-SMTP.com in this example) and gets the SMTP
server's mapped public IP address of 1.1.1.1.
Figure 71 LAN Computer Queries a Public DNS Server
144
xxx.LAN-SMTP.com = ?
1.1.1.1
LAN
192.168.1.21
DNS
xxx.LAN-SMTP.com = 1.1.1.1
192.168.1.89
NXC2500 User's Guide
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Troubleshooting
