Think of DNS to be like the phone book: to call Mr X Bloggs, you look up the name in some sort of paper or online phone book, call the number, and when there's an answer, you say "hello Mr Bloggs".... On yor PC, when you wish to go to "google.com", your PC needs to use DNS to find out which server to connect to (= its IP address) So how does DNS work? How does your PC know where to do DNS lookups? Most PCs will use DHCP to get their IP address as well as the IP address for the DNS server: at home,that typically comes from your broadband router. The router doesn't actually DO the DNS lookup itself, it typically asks your ISP to do so (the router learned that as part of it's "DHCP", when it connected to the ADSL). Your ISP will then go and do a "full DNS resolve", starting with the ROOT servers, then go to Nominet (who look after the .uk domain), then in my case, to NamesCo, who hosts my DNS. Plusnet then caches that information, an...
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 c...