Exercise 1: Layer 4 vs. Layer 7 Load Balancers — Possible Solution
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Explanation:

Per the chapter's own table, Layer 4 (Transport) is where "TCP, UDP,
ports" operate, while Layer 7 (Application) is where "HTTP, DNS, SSH"
operate. A load balancer's own job is to decide which backend server
should handle a given piece of traffic -- what differs between the two
types is exactly how much information about that traffic they're able
to see and use to make that decision.

A Layer 4 load balancer only has access to Transport-layer
information -- source/destination IP addresses and ports, and basic
TCP/UDP connection details. It can distribute traffic based on things
like "which server has the fewest active connections" or a simple
round-robin across IP:port combinations, but it has no visibility at
all into what's actually inside the traffic -- it can't read an HTTP
URL path, a hostname, or a cookie, because none of that exists yet at
the layer it operates on. It's fast and simple precisely because it
isn't inspecting or understanding the application data being carried.

A Layer 7 load balancer operates at the Application layer, meaning it
actually understands the protocol being carried -- per the chapter's
own example, HTTP specifically. This lets it make routing decisions
based on the actual content of a request: the URL path (e.g. routing
/api/* to one set of servers and /images/* to another), the hostname
in the request, cookies, or headers. This is strictly more capable
than a Layer 4 load balancer, but it also requires more processing
work, since it has to actually parse and understand the application
protocol rather than just reading connection-level metadata.

The colleague's proposed switch from Layer 4 to Layer 7 would trade
some raw simplicity/speed for the ability to make smarter,
content-aware routing decisions -- a real, practical tradeoff directly
explained by which OSI layer each type of load balancer actually
operates at.

WHY THIS WORKS AS AN ANSWER
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This explains specifically what information is and isn't visible at
each layer (connection metadata only vs. actual application content),
using the chapter's own table entries for layers 4 and 7, rather than
a vague "Layer 7 is smarter."