Cisco CCNA mock exam questions sample test – Question 405

.Which two are NOT features of Cisco NAT implementation? (Choose two.)

A. overload
B. override
C. overrule
D. static NAT
E. dynamic NAT

Correct Answer: BC

Explanation:
Override and overrule are NOT features of Cisco’s Network Address Translation (NAT) implementation. NAT translates internal IP address to external IP address and vice versa. NAT
is typically used by firewalls or routers.
The following are some of the characteristics of NAT:
It can act as an address translator between Internet and the local network.
It conserves IP addresses and simplifies the process of IP address allocation.
It allows the local network to connect to Internet using unregistered IP addresses.
It can present only one address for the entire network to the outside world when using dynamic NAT.
It enhances network security, as it does not disclose internal network addresses to the outside world.
All of the other options are incorrect because they are valid NAT features.
With static NAT, translation mappings are created statically and are placed in the translation tables whether or not there is traffic flowing. In this case, no registered addresses are
saved because a registered address is still required for each mapping.
With dynamic NAT, the translation table is populated as the required traffic flows through NAT-enabled devices. In this case, a single address or multiple public addresses can be
used multiple times to represent multiple private addresses.
The overload keyword allows the ip nat inside command to translate multiple devices in the internal network to the single address in the IP address pool. This process is also called
overloading in that the same public IP address is mapped to all private addresses from inside the network. Since the router performing the NAT overload function will use the unique
TCP source port from each host for identification, while mapping all of them to the same public IP address, it is sometimes referred to as Port Address Translation or PAT.
For example:
ip nat pool test 172.28.15.1 172.28.15.1 prefix 24
In this example, the NAT pool named “test” only has a range of one address.
Another variant of this command is given below, which configures NAT to overload on the address assigned to the serial 0 interface:
ip nat inside source list 3 interface serial 0 overload
When this variation is used, the command uses a list named 3 to determine the addresses in the pool.
Objective:
Infrastructure Services
Sub-Objective:
Configure, verify, and troubleshoot inside source NAT
References:
Cisco > Technology Support > IP > IP Routing > Design Technotes > Configuring Network Address Translation: Getting Started > Document ID: 13772 > Quick Start Steps for
Configuring and Deploying NAT