4.1 Inside Source NAT Flashcards
Configure and verify inside source NAT using static and pools. (23 cards)
What does NAT stand for, and what is its purpose?
Network Address Translation
It modifies IP address information in packet headers to allow multiple devices on a private network to share a single public IP address when accessing external networks, like the internet.
List the types of addresses associated with NAT operations.
- Inside local
- Inside global
- Outside local
- Outside global
Inside Local – Private IP assigned to an internal device, not routable on the internet.
Inside Global – Public IP mapped to an inside local address for external communication.
Outside Local – Private IP representing an external device from the internal network’s view.
Outside Global – Public IP of an external device, used for internet routing.
What command configures a router interface for internal static NAT?
ip nat inside
This command designates the router interface as part of the internal network for NAT operations.
How can an administrator set up static mappings in a NAT configuration?
ip nat inside source static
This command allows the administrator to define static NAT mappings by specifying the inside-local and inside-global addresses.
What command configures a public address pool for dynamic NAT?
ip nat pool
This command is essential for defining a range of public addresses that will be utilized for dynamic NAT translations.
What does Static NAT do?
It maps a private IP to a public IP.
Static NAT provides a one-to-one mapping between private and public addresses, ensuring a consistent external IP.
What does the term ‘inside global’ indicate in NAT?
A public IP assigned to an internal host.
The inside global address is the public IP that represents an internal host when packets travel on the Internet.
What is the main difference between static NAT and dynamic NAT?
- Static NAT uses fixed mappings.
- Dynamic NAT assigns from a pool.
Dynamic NAT automatically assigns addresses from a predefined range, allowing multiple hosts to share a limited number of public IPs.
What happens when all addresses in the dynamic NAT pool are in use?
New connections are dropped until an entry expires.
NAT dynamically assigns addresses, but if all are used, additional requests cannot be translated.
What is the purpose of the NAT table?
It stores active NAT mappings.
The NAT table tracks inside local to inside global mappings, ensuring proper address translation.
What happens to dynamic NAT table entries after a period of inactivity?
They time out and return to the pool.
Dynamic NAT entries expire after a period of inactivity to optimize resource usage.
What command is used to clear dynamic NAT entries from the table?
clear ip nat translation *
This command removes all dynamic NAT translations.
What is the role of the ‘ip nat outside’ command?
It configures interfaces to be in the outside part of the NAT design.
It is necessary for defining the external-facing portion of NAT operations.
What command is used to configure a static NAT mapping?
ip nat inside source static <inside-local-ip> <outside-global-ip></outside-global-ip></inside-local-ip>
This command creates a static entry that should not be removed from the NAT table.
What does the command ‘show ip nat translations’ display?
Active NAT table entries
This command shows inside local to inside global mappings, verifying proper NAT function.
True or False:
Dynamic NAT requires static mappings for IP addresses.
False
Dynamic NAT assigns addresses from a pool instead of requiring static mappings.
How does the NAT pool size affect dynamic NAT?
It controls the number of devices that can use a public IP.
A larger pool allows more simultaneous connections.
What is the purpose of an access control list (ACL) in dynamic NAT?
It identifies internal IPs for translation.
The ACL determines which private addresses should be translated to public IPs.
What command checks NAT statistics?
show ip nat statistics
This command provides detailed statistics on active NAT translations, packet hits, and misses.
What does the command clear ip nat translation *’ do?
It clears all NAT table entries.
This resets all dynamic translations, allowing fresh mappings.
What is the significance of the ‘ip nat pool’ command?
It defines a range of public IP addresses.
These addresses are used in dynamic NAT for outbound traffic translation.
True or False:
The destination IP address changes during the NAT process.
False
The destination IP address remains unchanged; only the source address is translated.
What typically causes NAT not to create translations in a lab setting?
No traffic passing through NAT.
NAT requires packets to pass through the router for translations to occur.
