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===== Static NAT Configuration =====
Static NAT requires few configuration steps. Each static mapping between local and global addresses **must** be configured. Not unlike a static entry for every static IP address required. You must inform the router on which interfaces to use ''**NAT**''. Interface subcommands inform the router which interfaces are ''**inside**'' / ''**outside**''.
  - ''**ip nat inside**'' command on an interface to specify inside.
  - ''**ip nat outside**'' command on an interface to specify outside.
  - ''**ip nat inside source static inside-local inside-global**'' from global config to configure the static mappings.
  - inside local will be a LAN IP - inside global will be your public IP (an EXTRA public IP).
===== Port Address Translation =====
Create an access list to match a group of source addresses as needed -- why else would we overload?
<code>
R1(config-std-nacl)#permit 10.1.1.0 0.0.0.255

R1#sh access-lists 
Standard IP access list NAT
    10 permit 10.1.1.0, wildcard bits 0.0.0.255 (2 matches)
    20 deny   any
</code>
Then configure NAT to match against entries in the NAT list configured above. Specify ''**OVERLOAD**'' to enable PAT.
<code>
ip nat inside source list MY_LIST int fa0/0 OVERLOAD
</code>

===== Verify NAT =====
<code>
R1#sh ip nat statistics 
Total active translations: 0 (0 static, 0 dynamic; 0 extended)
Outside interfaces:
  FastEthernet0/0, Serial0/0
Inside interfaces: 
  FastEthernet0/1, Loopback0
Hits: 16  Misses: 2
CEF Translated packets: 18, CEF Punted packets: 0
Expired translations: 2
Dynamic mappings:
-- Inside Source
[Id: 2] access-list NAT interface FastEthernet0/0 refcount 0
Appl doors: 0
Normal doors: 0
Queued Packets: 0

R1#sh ip nat translations 
Pro Inside global      Inside local       Outside local      Outside global
icmp 2.2.2.1:1         10.1.1.1:1         2.2.2.2:1          2.2.2.2:1
icmp 2.2.2.1:11        10.1.1.3:11        2.2.2.2:11         2.2.2.2:11


</code>
==== Clear NAT Translations ====
Useful with dynamic NAT in the event you run out of dynamic addresses to translate to. Clearing translations will free up slots if the clearout timer isn't quick enough.
<code>
R1#clear ip nat translation *
</code>

===== Chapter Questions =====
==== One ====
**Examine the following show command output on a router configured for dynamic NAT:**
<code>
-- Inside Source

access-list 1 pool fred refcount 2288

 pool fred: netmask 255.255.255.240

    start 200.1.1.1 end 200.1.1.7

    type generic, total addresses 7, allocated 7 (100%), misses 965
Users are complaining about not being able to reach the Internet. Which of the following is the most likely cause?
</code>
 
''**The NAT pool does not have enough entries to satisfy all requests.**''

The problem is not related to NAT, based on the information in the command output.

The command output does not supply enough information to identify the problem.

Standard ACL 1 cannot be used; an extended ACL must be used.
You answered this question correctly. ×

**Explanation:**
The last line mentions that the pool has seven addresses, with all seven allocated, with the misses counter close to 1000 - meaning that close to 1000 new flows were rejected because of insufficient space in the NAT pool.
==== Two ====
**Which of the following summarized subnets represent routes that could have been created for CIDR’s goal to reduce the size of Internet routing tables?**

 
200.1.1.0 255.255.255.0

''**200.1.0.0 255.255.0.0**''

10.1.0.0 255.255.0.0

10.0.0.0 255.255.255.0
You answered this question correctly. ×

**Explanation:**
CIDR’s original intent was to allow the summarization of multiple Class A, B, and C networks to reduce the size of Internet routing tables. Of the answers, only 200.1.0.0 255.255.0.0 summarizes multiple networks.

==== Three ====
**With static NAT, performing translation for inside addresses only, what causes NAT table entries to be created?**

  * ''**Configuration using the ip nat inside source command**''
  * The first packet from the inside network to the outside network
  * Configuration using the ip nat outside source command
  * The first packet from the outside network to the inside network
You answered this question correctly. ×

**Explanation:
**With static NAT, the entries are statically configured. Because the question mentions translation for inside addresses, the inside keyword is needed in the command.
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