300-115 Exam Free-300 115 Exam Questions

300-115
300-115 Background Information
Some knowledge of operating systems 300-115 exam 300-115 exam topics would help. The networking code, like any other component of the operating system, must follow both common sense and implicit rules for coexistence with the rest of the kernel, including proper use of locking; fair use of memory and CPU; and an eye toward modularity, code cleanliness, and good performance. Even though I occasionally spend time on those aspects, I refer you to the other two O’Reilly kernel books mentioned earlier for a deeper and detailed discussion on generic operating system services and design. Some knowledge of networking, and especially IP, would also help. However, I think the theory overview that precedes each implementation description in this book is sufficient to make the book self-contained for both newcomers and experienced readers. The theoretical description of the topics covered in the book does not require any programming experience. However, the descriptions of the associated implementations require an intermediate knowledge of the C language. Chapter 1 will go through a series of coding conventions and tricks that are often used in the code, which should help especially those with less experience with C and kernel programming.

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Organization of the Material
Some aspects of networking code require as many as seven chapters, while for other aspects one chapter is sufficient. When the topic is complex or big enough to span different chapters, the part of the book devoted to that topic always starts with a concept chapter that covers the theory necessary to understand the implementation, which is described in another chapter. All of the reference and secondary material is usually located in one miscellaneous chapter at the end of the part. No matter how big the topic is, the same scheme is used to organize its presentation. For each topic, the implementation description includes:

The big picture, which shows where the described kernel component falls in the network stack. A brief description of the main data structures and a figure that shows how they relate to each other. A description of which other kernel features the component interfaces withfor example, by means of notification chains or data structure cross-references. The firewall is an example of such a kernel feature, given the numerous hooks it has all over the networking code. Extensive use of flow charts and figures to make it easier to go through the code and extract the logic from big and seemingly complex functions.

The reference material always includes:

A detailed description of the most important data structures, field by field A table with a brief description of all functions, macros, and data structures, which you can use as a quick reference A list of the files mentioned in the chapter, with their location in the kernel source tree A description of the interface between the most common user-space tools used to configure the topic of the chapter and the kernel A description of any file in /proc that is exported

The Linux kernel’s networking code is not just a moving target, but a fast runner. The book does not cover all of the networking features. New ones are probably being added right now while you are reading. Many new features are driven by the needs of single users or organizations, or as university projects, but they find their way into the official kernel when they’re considered useful for a large audience. Besides detailing the implementation of a subset of those features, I try to give you an idea of what the generic implementation of a feature might look like. This will help you greatly in understanding changes to the code and learning how new features are implemented. For example, given any feature, you need to take the following points into consideration:

How do you design the data structures and the locking semantics? Is there a need for a user-space configuration tool? If so, is it going to interact with the kernel via an existing system call, an ioctl command, a /proc file, or the Netlink socket? Is there any need for a new notification chain, and is there a need to register to an already existing chain? What is the relationship with the firewall? Is there any need for a cache, a garbage collection mechanism, statistics, etc.?

Here is the list of topics covered in the book:

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Interface between user space and kernel In Chapter 3, you will get a brief overview of the mechanisms that networking configuration tools use to interact with their counterparts inside the kernel. It will not be a detailed discussion, but it will help you to understand certain parts of the kernel code.
System initialization Part II describes the initialization of key components of the networking code, and how network devices are registered and initialized.

Interface between deviceĀ 300-115 exam cost 300-115 exam questions drivers and protocol handlers Part III offers a detailed description of how ingress (incoming or received) packets are handed by the device drivers to the upper-layer protocols, and vice versa.

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