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You're reading from Network Analysis using Wireshark Cookbook This book will be a massive ally in troubleshooting your network using Wireshark, the world's most popular analyzer. Over 100 practical recipes provide a focus on real-life situations, helping you resolve your own individual issues.

Product type Paperback

Published in Dec 2013

Publisher Packt

ISBN-13 9781849517645

Length 452 pages

Edition 1st Edition

Tools

Wireshark

Concepts

Network Security

Author (1):

Yoram Orzach

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Table of Contents (17) Chapters

Preface

1. Introducing Wireshark FREE CHAPTER

2. Using Capture Filters

3. Using Display Filters

4. Using Basic Statistics Tools

5. Using Advanced Statistics Tools

6. Using the Expert Infos Window

7. Ethernet, LAN Switching, and Wireless LAN

8. ARP and IP Analysis

9. UDP/TCP Analysis

10. HTTP and DNS

11. Analyzing Enterprise Applications' Behavior

12. SIP, Multimedia, and IP Telephony

13. Troubleshooting Bandwidth and Delay Problems

14. Understanding Network Security

A. Links, Tools, and Reading

Index

Analysing DNS problems

In the previous recipe, we saw how to identify a normal operation of DNS. In this recipe, we will learn how to discover problematic behavior of DNS, and how to figure out its source.

Getting ready

A DNS problem can result in bad performance while browsing the Internet, slow network while working inside the organization network, or any other performance issues. We will see how to isolate these problems and how to find out whether it is a DNS issue or not.

How to do it...

There are two major types of problems in DNS:

DNS cannot resolve a name
Slow operation of DNS

In both cases, connect your Wireshark to the network in the following order when you suspect an Internet connectivity problem:

First, port mirror the PC of the customer complaining about the problem. In this step, you will see specific problems on the PC.
Then, port mirror your DNS server. In this step, you will be able to find the general problems that are common to the entire organization (or at least to the part...