Érdekes kis apróságra akadtam. A fenti cucc egy alkalmazásszintű router, amivel IIS-ekből álló webfarm gépeire lehet szelektíven ráirányítani a terhelést.
Tehát nem azt csinálja, mint az NLBS, hogy IP szinten dönt, hanem általunk megírt logika alapján osztja szét a terhelést a webszerverek között, ami adott esetben igen hasznos lehet.
Még nem látom át hogyan lehet ezzel kiküszöbölni a single point of failure-t, de rajta fogom tartani a szemem.

# HTTP based routing decisions
Unlike hardware load balancers that make the routing decisions at the IP level, Application Request Routing makes the routing decisions at the application level. Working with URL rewrite module, powerful routing rules can be written based on HTTP headers and server variables.
# Load balance algorithms
A user selected load balance algorithm is applied to determine which content server is most appropriate to service the HTTP requests. Six algorithms are provided.
# Health monitoring
Both live traffic and specific URL test are used to determine the health of content servers. A set of configuration parameters are provided to define the meaning of server health.
# Client affinity
Using a cookie, Application Request Routing can affinitize all requests from a client to a content server. It differentiates the clients behind NAT, so each client is treated independently. This feature requires that the clients accept cookies.
# Host name affinity
“Host name affinity” is a specific feature for shared hosters. It changes the deployment topology to minimize and streamline administration and to create additional business opportunities.
# Multiple server groups
Application Request Routing can manage multiple server groups, which are logical groupings of content servers in an environment. This feature allows Application Request Routing to be used in pilot management and A/B testing scenarios.
# Management and monitoring via UI
All configuration settings and aggregated runtime statistics of Application Request Routing are managed and viewable via IIS Manager.
# Failed Request Tracing Rules
Specific traces have been added to quickly troubleshoot and diagnose Application Request Routing.

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