Last time I looked at the CNS-218, which is the first 3 days of the CNS-220 course. This time, I'll look at the CNS-219, which takes a deep dive into the ADC side of the Netscaler features.
Just like the CNS-218, the CNS-219 is a mix of instruction and labs. Lets see what the 2 days covers:
Day 4:
Module 1: Classic Policies
Module 2: Default Policies
Module 3: Rewrite, Responder, and URL Transform
Day 5:
Module 4: Content Switching
Module 5: Secure Web Gateway
Module 6: Optimization
Module 7: GSLB
Module 8: Clustering (Optional Self Study)
Much of these 2 days is all about policies, and the features that are driven by policies. It's interesting that, when I teach these 2 days, my students tend to fall into one of 2 camps:
- Netscaler "beginners", need the basic LB stuff, don't really see the need for policies and all these fancy features.
- More experienced admins, understand LB, now looking to see how policies can do some useful stuff.
Of course, many of that first group will, sooner or later, appreciate that "all thse fancy features" can be not only useful, but essential!
It's very clear with version 12 code that, finally, Classic polices are starting to be "wound down", replaced by equivalent features that use the Default policy system (eg Content Filters replaced by Responder). However, the simplicity of the Classic polies make it a great place to start.
Ok, so lets take a dive into each of those modules... and yeah, as this is nominally a different course, we start at zero again!
Module 0: Course overview
Unless we have new students, joining for just the last 2 days, this tends to be no more than a 5 minute look at the agenda for the Thursday and Friday.
Module 1: Classic Policies
Using Content Filtering as an example, we introduce Policies, which allows us to make decisions, and the 2 versions that Netscaler has (and why!). We explain the (rather limited) abilities of PEs, and the whole concept of the way they work, with inline and named expressions. It's far from complex, but nicely sets the "ground rules" for the more complex PIs (=Default Policies). I also make sure that students are aware of the interactions between Classic policies bound at different levels
Module 2: Default Policies
In a way, this just continues the discussion on Policies, but we explain how much more powerful PIs are than PEs, giving several examples of the capabilities of the syntax: I try and equate the capabilities to the sort of features you would expect to see in other scripting languages, like Perl... if you want to do something, you assume it can be done, and search for the way to do it! Bindings for PIs is quite different from PEs, so I always walk through how that works. The lab for this module look at HTTP Callout and Rate Limiting, which is a bit odd, but they are a couple of neat features.
Module 3: Rewrite, Responder, and URL Transform
So having discussed the syntax and policy bindings in Module 2, we look at probably the 2 most important features driven by PIs, Rewrite and Responder. We see the various actions available to us, and how some of those actions will themselves use the PI syntax. The labs for this module are quite extensive, demonstrating several good (and real world) uses for these features. Some of the lab exercises are optional: from a trainer's perspective, this is good, as the more experienced students will have a bit more to do, so less likely to get bored, whilst the slower, less experienced students don't feel they are slowing things down.
So that's Thursday - a day about policies.... and of course, that's not the end of it, as we start Friday by looking at Content Switching, another policy-driven feature.
Module 4: Content Switching
I explain CS by explaining that it's a way to have a single entry-point into a Netscaler, with the policies splitting out which servers at the backend do what. It's also a great point to remind everyone that Netscaler Policies aren't just about HTTP traffic: there are some cool tricks you can do with things like Datastream, that can make your infrastructure work more efficiently... and a good time to remember what I said on day 1, about Netscaler being a tool to give your customers a better experience plus make your servers work better.
Module 5: Secure Web Gateway
Now here's a module that, in my opinion, is just out of place on this course. As such, I would briefly explain what it is about, and (unless anyone is really interested) not go into much detail. Generally, I'd move this module to the end of the day.
Module 6: Optimization
Originally, this module was dropped, in favour of the Secure Web Gateway module, but it's back again, which I think is good, as - whilst it doesn't go into a lot of detail - it introduces a whole load of useful Netscaler features: Compression, Caching, and Front End Optimisation. This VERY much a module about "making the Client experience better". FEO came from the Byte Mobile acquisition, and was all about improving the exoerience for mobile users... but heck, why shouldn't EVERYONE get that improved experience. (Of course, if web designers really took the time to understand how to create a web site properly, we wouldn't need to optimise it... they would have already done that!). Apart from a trivial compression lab, there's no hands on for these subjects (although we DO go into a lot more details on the CNS-320 advanced course!)
Module 7: GSLB
GSLB is one of those features that, once you understand what's going on, is actually not that complex: it's no more than site-to-site LB, using DNS as a means unto an end. I tend to ignore the slides (ok, I do go through them after, just in case I missed something!), and do this on the whiteboard, building up the picture of how it all connects together, whilst demonstrating the (actually quite simple) steps needed on the Netscaler. The lab demonstrates how to set up a 2-site GSLB setup, and the lab instructions become a good reference document for setting up GSLB for real. The GSLB modul can be a bit heavy, so I usually run this in the morning, rather than leaving until Friday afternoon!
Module 8: Clustering (Optional Self Study)
My experience in Europe is that very few students coming on the CNS-220 have any interest in Clustering. Its a feature needed by larger organisations, and as a resukt, Citrix normally interect with those custimers directly. So I was very happy that, whilst the module is kept, it's there for "self study". If there's time, I'll usually spend 10 minutes giving an overview, mainly to bring home the point that it's quite a bit more complex than HA!
So there you go, a round up of what you can expect in a CNS-220 course.
Next time, I'll take a look at the CNS-222, which covers the Netscaler Gateway feature. The first 3 days are the same as this course, with the Thursday and Friday being a deep dive into the NG feature.
Also, if you've already attended the CNS-220, then you can just take the 2 day CNS-221 to "top up" your knowledge.
Just like the CNS-218, the CNS-219 is a mix of instruction and labs. Lets see what the 2 days covers:
Day 4:
Module 1: Classic Policies
Module 2: Default Policies
Module 3: Rewrite, Responder, and URL Transform
Day 5:
Module 4: Content Switching
Module 5: Secure Web Gateway
Module 6: Optimization
Module 7: GSLB
Module 8: Clustering (Optional Self Study)
Much of these 2 days is all about policies, and the features that are driven by policies. It's interesting that, when I teach these 2 days, my students tend to fall into one of 2 camps:
- Netscaler "beginners", need the basic LB stuff, don't really see the need for policies and all these fancy features.
- More experienced admins, understand LB, now looking to see how policies can do some useful stuff.
Of course, many of that first group will, sooner or later, appreciate that "all thse fancy features" can be not only useful, but essential!
It's very clear with version 12 code that, finally, Classic polices are starting to be "wound down", replaced by equivalent features that use the Default policy system (eg Content Filters replaced by Responder). However, the simplicity of the Classic polies make it a great place to start.
Ok, so lets take a dive into each of those modules... and yeah, as this is nominally a different course, we start at zero again!
Module 0: Course overview
Unless we have new students, joining for just the last 2 days, this tends to be no more than a 5 minute look at the agenda for the Thursday and Friday.
Module 1: Classic Policies
Using Content Filtering as an example, we introduce Policies, which allows us to make decisions, and the 2 versions that Netscaler has (and why!). We explain the (rather limited) abilities of PEs, and the whole concept of the way they work, with inline and named expressions. It's far from complex, but nicely sets the "ground rules" for the more complex PIs (=Default Policies). I also make sure that students are aware of the interactions between Classic policies bound at different levels
Module 2: Default Policies
In a way, this just continues the discussion on Policies, but we explain how much more powerful PIs are than PEs, giving several examples of the capabilities of the syntax: I try and equate the capabilities to the sort of features you would expect to see in other scripting languages, like Perl... if you want to do something, you assume it can be done, and search for the way to do it! Bindings for PIs is quite different from PEs, so I always walk through how that works. The lab for this module look at HTTP Callout and Rate Limiting, which is a bit odd, but they are a couple of neat features.
Module 3: Rewrite, Responder, and URL Transform
So having discussed the syntax and policy bindings in Module 2, we look at probably the 2 most important features driven by PIs, Rewrite and Responder. We see the various actions available to us, and how some of those actions will themselves use the PI syntax. The labs for this module are quite extensive, demonstrating several good (and real world) uses for these features. Some of the lab exercises are optional: from a trainer's perspective, this is good, as the more experienced students will have a bit more to do, so less likely to get bored, whilst the slower, less experienced students don't feel they are slowing things down.
So that's Thursday - a day about policies.... and of course, that's not the end of it, as we start Friday by looking at Content Switching, another policy-driven feature.
Module 4: Content Switching
I explain CS by explaining that it's a way to have a single entry-point into a Netscaler, with the policies splitting out which servers at the backend do what. It's also a great point to remind everyone that Netscaler Policies aren't just about HTTP traffic: there are some cool tricks you can do with things like Datastream, that can make your infrastructure work more efficiently... and a good time to remember what I said on day 1, about Netscaler being a tool to give your customers a better experience plus make your servers work better.
Module 5: Secure Web Gateway
Now here's a module that, in my opinion, is just out of place on this course. As such, I would briefly explain what it is about, and (unless anyone is really interested) not go into much detail. Generally, I'd move this module to the end of the day.
Module 6: Optimization
Originally, this module was dropped, in favour of the Secure Web Gateway module, but it's back again, which I think is good, as - whilst it doesn't go into a lot of detail - it introduces a whole load of useful Netscaler features: Compression, Caching, and Front End Optimisation. This VERY much a module about "making the Client experience better". FEO came from the Byte Mobile acquisition, and was all about improving the exoerience for mobile users... but heck, why shouldn't EVERYONE get that improved experience. (Of course, if web designers really took the time to understand how to create a web site properly, we wouldn't need to optimise it... they would have already done that!). Apart from a trivial compression lab, there's no hands on for these subjects (although we DO go into a lot more details on the CNS-320 advanced course!)
Module 7: GSLB
GSLB is one of those features that, once you understand what's going on, is actually not that complex: it's no more than site-to-site LB, using DNS as a means unto an end. I tend to ignore the slides (ok, I do go through them after, just in case I missed something!), and do this on the whiteboard, building up the picture of how it all connects together, whilst demonstrating the (actually quite simple) steps needed on the Netscaler. The lab demonstrates how to set up a 2-site GSLB setup, and the lab instructions become a good reference document for setting up GSLB for real. The GSLB modul can be a bit heavy, so I usually run this in the morning, rather than leaving until Friday afternoon!
Module 8: Clustering (Optional Self Study)
My experience in Europe is that very few students coming on the CNS-220 have any interest in Clustering. Its a feature needed by larger organisations, and as a resukt, Citrix normally interect with those custimers directly. So I was very happy that, whilst the module is kept, it's there for "self study". If there's time, I'll usually spend 10 minutes giving an overview, mainly to bring home the point that it's quite a bit more complex than HA!
So there you go, a round up of what you can expect in a CNS-220 course.
Next time, I'll take a look at the CNS-222, which covers the Netscaler Gateway feature. The first 3 days are the same as this course, with the Thursday and Friday being a deep dive into the NG feature.
Also, if you've already attended the CNS-220, then you can just take the 2 day CNS-221 to "top up" your knowledge.
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