A beginner DNS presentation from RIPE NCC that shows how a simple DNS query is resolved «behind the scenes»…

Announcement follows:

The RIPE NCC is pleased to announce the launch of the first module of our DNSSEC e-learning course, entitled «DNS Basics».

This introductory module explains how DNS works by following a simple query, and can be viewed at:

In the coming months we will be releasing several more modules. Next up are:

Module 2: DNS Vulnerabilities
Module 3: DNSSEC

The RIPE NCC E-Learning Centre is a free-of-charge service available to everyone. If you have any questions, please feel free to contact us at <>.

Happy Learning,

Rumy Kanis
Training Services Manager


CDP for linux

Network Inventory .. What a nightmare to keep up-to-date!

Luckily, if you use Cisco switches, CDPR is here to help you discover where do all your network cables end up.. Simply run it on your linux server, wait a few seconds, and your cisco switch will broadcast the info.

Read about it at

The opposite is also useful as well..  A daemon run on linux systems that speaks Cisco Discovery Protocol, thus showing up on your switch’s cdp neighborhood ..

I found cdp-send of cdp-tools that works, but ladvd works better with bonding :)

sw-02>show cdp neighbors
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
 S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone

Device ID        Local Intrfce     Holdtme    Capability  Platform  Port ID
sw-01            Fas 0/23           150          S I      WS-C3550-1Gig 0/4
router-01        Fas 0/24           158           R       3640      Fas 0/0
linux.local      Fas 0/19           176           H       Linux     eth0

sw-02>show cdp neighbors detail
Device ID: linux.local
Entry address(es):
 IP address:
Platform: Linux,  Capabilities: Host
Interface: FastEthernet0/19,  Port ID (outgoing port): eth0
Holdtime : 160 sec

Version :
Linux 2.6.18-92.1.22.el5 #1 SMP Tue Dec 16 11:57:43 EST 2008 x86_64

advertisement version: 2
Duplex: full
Management address(es):