How would you scale the design of a messaging system that only involves emojis for users in Europe and US? How would you identify the origin of traffic?

To scale a messaging system for European and US users, I would leverage GeoDNS to direct users to the nearest regional data centers, minimizing latency. For instance, DNS resolution would use GeoIP data to route European users to European servers and US users to US servers. A global load balancer would then distribute incoming traffic across available instances within each region. To identify traffic origin, GeoDNS is the primary mechanism. Additionally, application-level logs and analytics can capture user IP addresses, further confirming their geographical location and enabling targeted optimizations or regional feature rollouts.