NAT Questions
Note: If you are not sure about NAT PAT, please read our Network Address Translation NAT Tutorial.
Question 1
Question 2
Explanation
Maybe this question wanted to ask “which IP address is the source IP at the receiving side?” as there are two correct answers for inside local IP address (10.4.4.4 & 10.4.4.5) so they cannot be the correct answer.
Question 3
Explanation
By adding the keyword “overload” at the end of a NAT statement, NAT becomes PAT (Port Address Translation). This is also a kind of dynamic NAT that maps multiple private IP addresses to a single public IP address (many-to-one) by using different ports. Static NAT and Dynamic NAT both require a one-to-one mapping from the inside local to the inside global address. By using PAT, you can have thousands of users connect to the Internet using only one real global IP address. PAT is the technology that helps us not run out of public IP address on the Internet. This is the most popular type of NAT.
An example of using “overload” keyword is shown below:
R1(config)# ip nat inside source list 1 interface ethernet1 overload
Question 4
Explanation
NAT use four types of addresses:
* Inside local address – The IP address assigned to a host on the inside network. The address is usually not an IP address assigned by the Internet Network Information Center (InterNIC) or service provider. This address is likely to be an RFC 1918 private address.
* Inside global address – A legitimate IP address assigned by the InterNIC or service provider that represents one or more inside local IP addresses to the outside world.
* Outside local address – The IP address of an outside host as it is known to the hosts on the inside network.
* Outside global address – The IP address assigned to a host on the outside network. The owner of the host assigns this address.
Question 5
Explanation
The “ip nat inside” command was wrongly configured with inside local address of 192.168.11.254 while it should be 192.168.11.11, which is the IP address of the web server.
Question 6
Explanation
The command “ip nat inside source list 1 pool mypool” (notice the keyword “inside”, not “outside”).
This command translates all source addresses that pass access list 1, which means a source address from 10.10.0.0/24, into an address from the pool named mypool (the pool contains addresses from 192.168.3.1 to 192.168.3.3).
q2 why ans C ?
Q2 Im not sure C is the correct answer. I think the correct answer is D
i think the correct answer is D . it is beacuse when a nat has taken place the new source ip will be the inside global and the destined ip will be the outside global
I think author of Q2 meant the “source IP from which the communication reaches the target”. This would be 172.23.104.4
Q4. Outside local ip is not global ip addres?
The answer depends on the point of view.
From the inside view it is the inside local,
from the Nat router view it is the inside global.
I think we look here from the nat-router view then the source address is the inside global.
Answer D ist the correct Answer
@9tut could you please explain why option D is not the correct answer for question number 2?
in q#2 the source inside ip addrss is 172.23.104.4 i think the right answer is D
I would also confirm that answer for Q2 is D
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Q2 – C & D both can be correct answer.
When the engineer establishes telnet to the router source IP is 172.23.103.10 (outside local). But when an https connection is established source IP is 172.23.104.4 (inside global). I feel the question should have specified “from which connection point of view”.
I understand NAT/PAT, but in a real world network how would a client from a branch office connect to a (server or specific host in a head office). How would the Packet find its way, what would you use.
Thanks Patrick.
@9tut and @all: At Q2, 172.23.103.10 is the destination address, so I guess it’s not the correct answer. Please verify.
Hi, could someone say where are qustions ? I’v got only Mar_2022.pdf and I don’t see question for this answers
Thank God Q2 answer is D. I was trying my best to understand and workout why it was C. Cheers for the input.
no questions
The question is misleading for#2. Prob D. But why would you use a private address for inside global
More about Q2:
Without NAT command and looking at translation:
R1#show ip nat translations
Pro Inside global Inside local Outside local Outside global
tcp 172.23.104.3:43268 10.4.4.4:43268 172.23.103.10:23 172.23.103.10:23
tcp 172.23.104.4:45507 10.4.4.5:45507 172.23.103.10:80 172.23.103.10:80
Asking for a source only have two posibility 172.23.104.3 and 4, because of ports at Outside global, the are wellknown ports, ports of services, destiny ports of traffic started on then inside global side, the real source, in command:
ip nat inside source list (172.23.104.3,172.26.104.4,..) 172.23.103.10