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There are 3 types of NAT:
A. Network Address Translation (NAT) is designed for IP address conservation. It enables private IP networks that use unregistered IP addresses to connect to the Internet. This provides additional security by effectively hiding the entire internal network behind that address.
For example a computer on an internal address of 192.168. 1.10 wanted to communicate with a web server somewhere on the internet, NAT would translate the address 192.168. 1.10 to the company’s public address, lets call this 1.1.
But the days of Nat breaking applications have long since gone. Today, applications are written with the assumption that Nat will be used. This means that embedding IP addresses inside data packets – always a violation of networking standards – is now considered a poor coding practice.
To configure 1:1 NAT:
The good: NAT is relatively effective as a first line of defense against hackers who might invade your system. While it’s not perfect, it’s pretty darn effective. The bad: Doing any Web-based functions that require passing the IP address in the body of the message can have problems working through NAT.
According to Sony’s version, NAT Type 1 is the best, and NAT Type 3 is the worst. Here’s more on Sony’s NAT Types: NAT Type 1 – Open: The system is connected directly to the Internet. NAT Type 2 – Moderate: The system is connected to the Internet with a router.
Moreover for networking systems, NAT provides double feature of address translation and security. However NAT comes with advantages as well as disadvantages….Disadvantages of Network Address Translation
Additionally, NAT can provide security and privacy. Because NAT transfers packets of data from public to private addresses, it also prevents anything else from accessing the private device. The router sorts the data to ensure everything goes to the right place, making it more difficult for unwanted data to get by.
Using NAT has some benefits: You help in conserving the IPv4 address space (when you use NAT Overload). You increase the flexibility and the reliability of connections to the public network by implementing multiple pools, backup pools and load-balancing pools to. You have a consistent network addressing scheme.
NAT acts as a firewall with a “default deny” policy for unsolicited incoming packets, but no other rules. Because the machines behind a NAT box are not directly addressable (usually because they have private IP addresses), machines out on the general Internet cannot send IP packets to them directly.
Key Concept – NAT Overload is a special form of dynamic NAT that allows many-to-one mapping of local addresses to a smaller number global addresses from a pool of global addresses. The pool of global addresses may even consist of a single address. NAT Overload is also called Port Address Translation (PAT).
command debug ip nat
command clear ip nat translations
Routers operate on the third layer of the OSI Model, the Network-Control Layer. Rather than passing packets based on the Media Access Control (MAC) Layer addresses (as bridges do), a router examines the packet’s data structure and determines whether or not to forward it.
Which command is used to determine if an IP access list is enabled on a particular interface? Explanation: The show ip interface command will show you if any outbound or inbound interfaces have an access list set.
There are two versions of IP that currently coexist in the global Internet: IP version 4 (IPv4) and IP version 6 (IPv6). IP addresses are made up of binary values and drive the routing of all data over the Internet. IPv4 addresses are 32 bits long, and IPv6 addresses 128 bits long.
Solution(By Examveda Team) Only the show ip interface command will tell you which interfaces have access lists applied. show access-lists will not show you which interfaces have an access list applied.