101 · Question #1
Assume a client's traffic is being processed only by a NAT; no SNAT or virtual server processing takes place. Also assume that the NAT definition specifies a NAT address and an origin address while al
The correct answer is C. The source address would be changed to the NAT address and destination address would be left. On F5 BIG-IP, when an origin server initiates outbound traffic processed by a NAT, the source address is translated from the origin address to the NAT address, while the destination address remains unchanged.
Question
Assume a client's traffic is being processed only by a NAT; no SNAT or virtual server processing takes place. Also assume that the NAT definition specifies a NAT address and an origin address while all other settings are left at their defaults. If the origin server were to initiate traffic via the BIG-IP, what changes, if any, would take place when the BIG-IP processes such packets.
Options
- AThe BIG-IP would drop the request since the traffic didn arrive destined to the NAT address.
- BThe source address would not change, but the destination address would be changed to the NAT
- CThe source address would be changed to the NAT address and destination address would be left
- DThe source address would not change, but the destination address would be changed to a self-IP
How the community answered
(31 responses)- A10% (3)
- B3% (1)
- C84% (26)
- D3% (1)
Why each option
On F5 BIG-IP, when an origin server initiates outbound traffic processed by a NAT, the source address is translated from the origin address to the NAT address, while the destination address remains unchanged.
The BIG-IP does not drop origin-initiated packets; NATs on BIG-IP operate bidirectionally, processing traffic whether it arrives destined to the NAT address or sourced from the origin address.
When the origin server initiates traffic, it is the source address (origin address) that gets changed to the NAT address, not the destination; this choice incorrectly states the source remains unchanged.
A BIG-IP NAT maps a NAT address to an origin address bidirectionally. When the origin server initiates traffic, the BIG-IP performs forward NAT translation by replacing the source address (origin address) with the NAT address. The destination address is not modified because NAT only manipulates the address that corresponds to the defined origin-to-NAT mapping direction, leaving the packet's destination intact.
The BIG-IP does not change the destination to a self-IP during NAT processing; self-IPs are not substituted as destinations in NAT translations.
Concept tested: F5 BIG-IP NAT bidirectional address translation behavior
Source: https://techdocs.f5.com/en-us/bigip-15-1-0/big-ip-local-traffic-management-basics/nat.html
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