Podcast
Questions and Answers
What is the main reason why NAT is essential for the current Internet based on IPv4?
What is the main reason why NAT is essential for the current Internet based on IPv4?
What is the purpose of NAT in a server farm?
What is the purpose of NAT in a server farm?
What is the primary function of an edge router?
What is the primary function of an edge router?
What is the main benefit of using NAT in a home network?
What is the main benefit of using NAT in a home network?
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What is the consequence of IPv4 address exhaustion?
What is the consequence of IPv4 address exhaustion?
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What is the primary advantage of NAT as IP masquerading?
What is the primary advantage of NAT as IP masquerading?
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What happens when the destination IP:port matches the tcp NAT entry?
What happens when the destination IP:port matches the tcp NAT entry?
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What is the purpose of port forwarding?
What is the purpose of port forwarding?
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Which of the following services uses UDP port 53?
Which of the following services uses UDP port 53?
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What is the limitation of port forwarding?
What is the limitation of port forwarding?
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What is the purpose of the command 'ip nat inside source static udp 192.168.2.1 53 61.38.120.77 53'?
What is the purpose of the command 'ip nat inside source static udp 192.168.2.1 53 61.38.120.77 53'?
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What is the primary function of port forwarding?
What is the primary function of port forwarding?
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What is the maximum number of port numbers that can be redirected to a single private IP address using port forwarding?
What is the maximum number of port numbers that can be redirected to a single private IP address using port forwarding?
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What is the purpose of using a different external port number in the configuration 'R1(config)#ip nat inside source static tcp 192.168.2.2 80 200.1.1.2 2000'?
What is the purpose of using a different external port number in the configuration 'R1(config)#ip nat inside source static tcp 192.168.2.2 80 200.1.1.2 2000'?
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What is the term for the configuration where a private network goes through more than 1 stage of NAT (or PAT)?
What is the term for the configuration where a private network goes through more than 1 stage of NAT (or PAT)?
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What is the IP address that the hosts of the outside network will use to access the HTTP, Telnet, and FTP services?
What is the IP address that the hosts of the outside network will use to access the HTTP, Telnet, and FTP services?
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What is the term for the configuration 'R1(config)#ip nat inside source static tcp 192.168.2.1 80 200.1.1.2 80'?
What is the term for the configuration 'R1(config)#ip nat inside source static tcp 192.168.2.1 80 200.1.1.2 80'?
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What is the purpose of PAT in a wireless router?
What is the purpose of PAT in a wireless router?
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How does the world access a server in a private network?
How does the world access a server in a private network?
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What is the format of static NAT mapping in port forwarding?
What is the format of static NAT mapping in port forwarding?
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What happens to packets with a destination port 80 reaching the public IP in the example provided?
What happens to packets with a destination port 80 reaching the public IP in the example provided?
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What is the public IP address of the web server to the outside world?
What is the public IP address of the web server to the outside world?
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What is the purpose of the 'ip nat inside source static' command?
What is the purpose of the 'ip nat inside source static' command?
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What is the reason for other subnets, except 192.168.1.0, to undergo PAT?
What is the reason for other subnets, except 192.168.1.0, to undergo PAT?
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How does 172.16.5.0/24 access Server0?
How does 172.16.5.0/24 access Server0?
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What is the purpose of the commands starting with 'ip nat inside source static'?
What is the purpose of the commands starting with 'ip nat inside source static'?
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How does PC0 access all 4 private network servers via the public IP of 200.1.1.1?
How does PC0 access all 4 private network servers via the public IP of 200.1.1.1?
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What is the purpose of 'type rotary' in the NAT pool configuration?
What is the purpose of 'type rotary' in the NAT pool configuration?
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How is the load of incoming requests handled in TCP load distribution?
How is the load of incoming requests handled in TCP load distribution?
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Study Notes
NAT (Network Address Translation)
- One public IP can be used by thousands of private network computers
- NAT obscures an internal network's structure and makes all network traffic appear to originate from a single IP address of a router
Why NAT is Important
- IPv4 address exhaustion: NAT is crucial for IPv4 to function because there aren't enough IPv4 addresses to cater for every device
- Many institutions have only 1 public IP to cater for thousands of PCs behind the edge router
NAT for TCP Load Sharing
- Useful for server farms: multiple servers with similar functions can be represented by a single IP address
- Handles the load of incoming requests by spreading the load among several mirrored servers
Port Forwarding
- Also known as static NAT
- Maps a public IP and port number to a private IP and port number
- Allows external access to internal services behind a NAT router
- Examples of services that use UDP port forwarding: DNS (port 53) and TFTP (port 69)
Configuring Port Forwarding
- can be configured on a wireless router
- Redirects incoming traffic to internal servers
- Can map different local IPs and ports to a global IP and different ports
Double NAT/PAT
- A private network can go through more than one stage of NAT (or PAT) and still function properly
- Useful for security purposes
- Example: Double NAT/PAT configuration with PAT entries
PAT (Port Address Translation)
- Similar to NAT, but translates both IP addresses and port numbers
- Automatically performed by some wireless routers for the user
- Also known as IP masquerading
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Description
Learn about the features and applications of Network Address Translation (NAT) in IPv4 networks. Discover how NAT enables multiple private network computers to share a single public IP address, and its uses in server load balancing and obscuring internal network structures.