Crashes, No Sound, or Screen Glitches?
Random freezes, missing sound and display glitches usually trace back to one bad driver. Find and replace yours safely.Free scan · under a minuteWindows Errors? Fix Them Before They Spread
Repair common Windows errors and clear accumulated junk for a smoother, more stable PC - no reinstall needed.Free scan · no reinstalliTechGuides is reader-supported. When you buy through links on our site, we may earn an affiliate commission. As an Amazon Associate I earn from qualifying purchases. Learn more
A load balancer does more than take turns sending requests to servers. It applies routing rules, chooses which backends are eligible, and directs new requests or network flows according to the product’s capabilities and configuration. Round robin is one possible target-selection algorithm—not the whole job.
What does a load balancer do?
A load balancer gives clients a contact point and distributes traffic across a group of backend resources. The important operational role is deciding where new traffic goes: which rule applies, which backend pool is relevant, and which members of that pool may receive traffic.
The extent of that control depends on the load balancer’s layer. An application-layer proxy can inspect HTTP request details and route accordingly. A Layer 4 load balancer can distribute TCP or UDP flows using network-level information without reading the application payload.
How does it decide where traffic goes?
First, it applies routing policy
With an AWS Application Load Balancer (ALB), a listener accepts connections on configured ports and protocols. Its rules are evaluated in priority order. Conditions can use URL paths, host headers, HTTP headers, methods, query parameters, or source IP addresses. A matching rule can direct a request to a target group, making it possible to route different parts of an application to separate services through one listener and load balancer. See AWS’s ALB overview.
#1 Best Overall
- 【Five Gigabit Ports】1 Gigabit WAN Port plus 2 Gigabit WAN/LAN Ports plus 2 Gigabit LAN Port. Up to 3 WAN ports optimize bandwidth usage through one device.
- 【One USB WAN Port】Mobile broadband via 4G/3G modem is supported for WAN backup by connecting to the USB port. For complete list of compatible 4G/3G modems, please visit TP-Link website.
- 【Abundant Security Features】Advanced firewall policies, DoS defense, IP/MAC/URL filtering, speed test and more security functions protect your network and data.
- 【Highly Secure VPN】Supports up to 20× LAN-to-LAN IPsec, 16× OpenVPN, 16× L2TP, and 16× PPTP VPN connections.
- Security - SPI Firewall, VPN Pass through, FTP/H.323/PPTP/SIP/IPsec ALG, DoS Defence, Ping of Death and Local Management. Standards and Protocols IEEE 802.3, 802.3u, 802.3ab, IEEE 802.3x, IEEE 802.1q
Then, it selects an eligible target
After an ALB rule selects a target group, the ALB chooses a registered target from that group. AWS documents round robin as the default target-selection algorithm and least outstanding requests as an alternative. This choice answers a narrower question—how to select among targets in the chosen group—than the listener rules answer.
Layer 4 can make a different kind of decision
Azure Load Balancer operates at Layer 4. Its default five-tuple hash uses source IP address, source port, destination IP address, destination port, and protocol to distribute TCP or UDP flows. Two-tuple and three-tuple modes are also available and can provide session affinity. Because it does not inspect application payloads, Azure Load Balancer cannot route by URL path, rewrite HTTP headers, or offload TLS. The Azure Load Balancer algorithm documentation explains the distinction.
Rank #2
- 【Flexible Port Configuration】1 2.5Gigabit WAN Port + 1 2.5Gigabit WAN/LAN Ports + 4 Gigabit WAN/LAN Port + 1 Gigabit SFP WAN/LAN Port + 1 USB 2.0 Port (Supports USB storage and LTE backup with LTE dongle) provide high-bandwidth aggregation connectivity.
- 【High-Performace Network Capacity】Maximum number of concurrent sessions – 500,000. Maximum number of clients – 1000+.
- 【Cloud Access】Remote Cloud access and Omada app brings centralized cloud management of the whole network from different sites—all controlled from a single interface anywhere, anytime.
- 【Highly Secure VPN】Supports up to 100× LAN-to-LAN IPsec, 66× OpenVPN, 60× L2TP, and 60× PPTP VPN connections.
- 【5 Years Warranty】Backed by our 5-years warranty and free technical support from 6am to 6pm PST Monday to Fridays
| Decision | AWS Application Load Balancer | Azure Load Balancer |
|---|---|---|
| Traffic unit | Application requests | TCP or UDP flows |
| Routing input | Listener-rule conditions, including HTTP request content and source IP | Network tuple fields; five-tuple is the default |
| Backend selection | Round robin by default, or least outstanding requests | Hash-based distribution; two-tuple and three-tuple modes support affinity |
| Application-payload inspection | Yes, for supported application-layer routing | No |
These are examples, not interchangeable implementations of one universal algorithm. Choose based on the traffic unit and routing inputs the application needs.
The Tool Desk
Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →What happens when a backend fails?
Health checks affect eligibility
A health check tests a target according to configured criteria; it is not a guarantee that every application function is working. AWS ALB health checks are configured per target group and use HTTP or HTTPS GET requests. The configuration can include a path, interval, timeout, consecutive success and failure thresholds, and accepted response codes. A check against a port that is open but whose application is unable to serve requests may report a misleading picture.
Rank #3
- 【Flexible Port Configuration】1 Gigabit SFP WAN Port + 1 Gigabit WAN Port + 2 Gigabit WAN/LAN Ports plus1 Gigabit LAN Port. Up to four WAN ports optimize bandwidth usage through one device.
- 【Increased Network Capacity】Maximum number of associated client devices – 150,000. Maximum number of clients – Up to 700.
- 【Integrated into Omada SDN】Omada’s Software Defined Networking (SDN) platform integrates network devices including gateways, access points & switches with multiple control options offered – Omada Hardware controller, Omada Software Controller or Omada cloud-based controller(Contact TP-Link for Cloud-Based Controller Plan Details). Standalone mode also applies.
- 【Cloud Access】Remote Cloud access and Omada app brings centralized cloud management of the whole network from different sites—all controlled from a single interface anywhere, anytime.
- 【SDN Compatibility】For SDN usage, make sure your devices/controllers are either equipped with or can be upgraded to SDN version. SDN controllers work only with SDN Gateways, Access Points & Switches. Non-SDN controllers work only with non-SDN APs. For devices that are compatible with SDN firmware, please visit TP-Link website.
Azure Load Balancer probes can use TCP, HTTP, or HTTPS, depending on the SKU and configuration. For HTTP(S) probes, a response other than HTTP 200 is treated as a failure. Probe rules influence whether a backend receives new flows; they do not mean all active work instantly moves elsewhere. Azure documents cases in which established TCP flows can continue when all probes are down on Standard Load Balancer, while UDP behavior differs. The outcome must therefore be described in terms of SKU, protocol, and flow state, not as a generic “failed server” rule. See Microsoft’s Azure health-probe guidance.
All backends unhealthy does not always mean traffic stops
A critical AWS ALB exception: if every registered target in a target group is unhealthy, AWS says the ALB fails open and routes traffic to all registered targets regardless of health status. Do not assume that an unhealthy status always causes an ALB to stop sending traffic. The exact health-check configuration and all-targets-unhealthy behavior are described in AWS’s target-group health-check documentation.
Probe design is part of traffic policy
A probe should represent the health of the instance and the application service that is meant to receive traffic. Microsoft warns against probing through a backend appliance to another instance: a response from downstream can make an appliance appear healthy when it is not, or a downstream failure can mark it unhealthy and trigger cascading effects. A probe can also be intentionally used to remove an instance from new-flow service during maintenance, so its meaning should be explicit.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
Microsoft’s current Azure probe documentation lists a five-second interval as the Azure portal’s default, while noting that deployment interfaces can have different defaults; it lists 30 seconds as the built-in timeout for HTTP/S probes. These are documented configuration values, not recommended universal settings. Review the actual probe configuration and the service’s response behavior before relying on either number.
Best Value
- Multi-WAN Business Continuity: Connect up to 5 ISPs with automatic failover and load balancing — if one connection drops, traffic instantly reroutes to keep your business, remote office, or home lab online
- OpenWRT-Ready Enterprise Control: Full OpenWRT support unlocks VLAN segmentation, advanced firewall rules, custom QoS policies, and community-developed packages for professional-grade network management
- Complete VPN Gateway Suite: WireGuard, OpenVPN, IPsec, PPTP, and L2TP server and client built in; create site-to-site tunnels, host remote access, or route specific VLANs through encrypted VPN connections
- Professional Security Stack: SPI firewall, DoS attack prevention, IP/MAC binding, domain filtering, and DMZ hosting protect your network perimeter while keeping critical services accessible
- Flexible Deployment & Monitoring: Web GUI or Cudy App cloud management with TR-069 support; built-in diagnostic tools (Ping, Traceroute, NSLookup, system logs) for rapid troubleshooting anytime
Why topology and existing connections matter
Backend eligibility is only part of availability. The zones in which a load balancer and its targets operate, and whether traffic can cross zones, affect where requests land. AWS requires an ALB to use at least two enabled Availability Zones and recommends multiple zones. Its cross-zone behavior affects how a load-balancer node distributes its share of client traffic among targets. AWS also documents a 60-second DNS entry TTL for Elastic Load Balancing; that is a service-specific documented value, not a general DNS rule. Details are in AWS’s Elastic Load Balancing overview.
A zonal shift is a separate AWS recovery control that moves a resource away from an impaired Availability Zone. It should not be confused with an algorithm such as round robin, and existing connections may take time to complete. More broadly, changing backend eligibility or routing new traffic does not necessarily migrate active sessions or erase their state.
What to compare when choosing a load balancer
- Layer and traffic unit: Does the service route individual application requests or distribute network flows? Does it need to inspect HTTP content, or is TCP/UDP pass-through sufficient?
- Routing inputs and algorithm: Which request conditions or tuple fields can influence placement? Is the selection algorithm configurable, and is session affinity required?
- Health model: Which probe protocol and path are supported? What response counts as healthy, how many failures change status, and what happens if every backend is unhealthy?
- Failure and topology behavior: How does the product handle zones, cross-zone distribution, fail-open or fail-closed cases, and established connections?
- Operational visibility: Can operators see health metrics or logs, register and drain targets, and verify that the probe represents the actual application service?
For Azure-specific component terminology, the Azure Load Balancer components overview describes the frontend IP configuration, backend pool, rules, and health probes. Those pieces make the control boundary concrete: the frontend is the contact point, rules map traffic to backend resources, and probes inform new-flow eligibility.
Recommended Free Tools
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
