The extendable parameter of NAT, which causes an address to be tested by different interfaces NAT
one。 Test the topology:
two。 Basic ideas and written examination questions:
a. Basic ideas:
By using the NAT extendable parameter, an internal address can be NAT out with different addresses on different interfaces, otherwise an internal address can only be allocated with static NAT once.
b. Written examination questions:
An internal DNS server requires a NAT on a Cisco IOS router that is dual-homed to separate ISPs using distinct CIDR blocks. Which NAT capability is required to allow hosts in each CIDR block to contact the DNS server via one translated address?
Answer: NAT extendable
three。 Basic configuration:
A.R1 Router:
Interface Ethernet0/0
Ip address 202.100.1.2 255.255.255.0
No shut
B.R2 Router:
Interface Ethernet0/0
Ip address 61.1.1.2 255.255.255.0
No shut
C.R3 Router:
Interface Ethernet0/0
Ip address 10.1.1.1 255.255.255.0
Ip nat inside
No shut
Interface Ethernet0/1
Ip address 202.100.1.1 255.255.255.0
Ip nat outside
No shut
Interface Ethernet0/2
Ip address 61.128.1.1 255.255.255.0
Ip nat outside
No shut
D.R4 router
Interface Ethernet0/0
Ip address 10.1.1.2 255.255.255.0
Sno shut
Ip route 0.0.0.0 0.0.0.0 10.1.1.1
Line vty 0 5
Password cisco
Login
IV. NAT extendable configuration:
A.R3 Router:
Ip nat inside source static 10.1.1.2 61.128.1.8 extendable
Ip nat inside source static 10.1.1.2 202.100.1.8 extendable
b. Test:
R1#telnet 202.100.1.8
Trying 202.100.1.8... Open
User Access Verification
Password:
R4 > show users
Line User Host (s) Idle Location
0 con 0 idle 06:08:16
* 130 vty 0 idle 00:00:00 202.100.1.2
Interface User Mode Idle Peer Address
R2#telnet 61.128.1.8
Trying 61.128.1.8... Open
User Access Verification
Password:
R4 > show users
Line User Host (s) Idle Location
0 con 0 idle 06:09:06
130 vty 0 idle 00:00:49 202.100.1.2
* 131 vty 1 idle 00:00:00 61.128.1.2
Interface User Mode Idle Peer Address
