Quick Answer
The default EtherChannel load balancing method on Cisco switches is source MAC address. This means that when a switch has an EtherChannel configured, it examines the source MAC address of each incoming frame and assigns that frame to a specific physical link within the bundle based on a hash of that address. The reason this is the default is that it is simple and requires no additional configuration, but it can lead to uneven traffic distribution if a small number of hosts are generating most of the traffic, since all frames from the same source MAC will use the same link. On the ENCOR 350-401 exam, this topic tests your understanding of Layer 2 load balancing and the distinction between source-based and destination-based hashing. A common trap is assuming the default is destination MAC or IP-based, so remember that Cisco prioritizes simplicity out of the box. A useful memory tip is "S for Source, S for Standard"—the standard default is the source MAC.
This 350-401 practice question tests your understanding of etherchannel. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
What is the default load-balancing method used by Cisco switches for EtherChannel?
Source MAC address
Correct. The default is src-mac on most Cisco switches.
Destination MAC address
Why wrong: Incorrect. The default is not dst-mac; it is src-mac.
Source IP address
Why wrong: Incorrect. Source IP is not the default; it is an optional method.
Source and destination IP address
Why wrong: Incorrect. This is an optional method but not the default.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Source MAC address
Cisco switches default to source MAC address-based load balancing for EtherChannel. This method distributes traffic based on the source MAC address of the frame, which can lead to uneven distribution if traffic patterns are not diverse.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Source MAC address
Why this is correct
Correct. The default is src-mac on most Cisco switches.
Related concept
Static NAT maps one inside address to one outside address.
Destination MAC address
Why it's wrong here
Incorrect. The default is not dst-mac; it is src-mac.
Source IP address
Why it's wrong here
Incorrect. Source IP is not the default; it is an optional method.
Source and destination IP address
Why it's wrong here
Incorrect. This is an optional method but not the default.
Common exam traps
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related 350-401 NAT questions on configuration and troubleshooting.
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FAQ
EtherChannel — This question tests EtherChannel — Static NAT maps one inside address to one outside address..
The correct answer is: Source MAC address — Cisco switches default to source MAC address-based load balancing for EtherChannel. This method distributes traffic based on the source MAC address of the frame, which can lead to uneven distribution if traffic patterns are not diverse.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related 350-401 NAT questions on configuration and troubleshooting.
Static NAT maps one inside address to one outside address.
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Last reviewed: Jun 18, 2026
This 350-401 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 350-401 exam.
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