Collection of useful, relevant or inane places on the the Internets for 26th Aug:

• Practical Guide to Troubleshooting with Traceroute – Think you know all about Traceroute. Think again. Very well done presentation at NANOG on the ART of troubleshooting with Traceroute. If you need a practical reminder that not all in networking is as it seems, then this presentation covers some of the obvious mistakes that beginners make. Good insights into the gap between certification (theory) and experience (practice). They don't put this into the text books. (via @pello)
• IETF RFC 5625 – DNS Proxy – good meaty troubleshooting tips to be found in here. – This IETF RFC on DNS Proxy is full of meaty goodness about real life problems with DNS and Firewalls. While specifically target at low cost ADSL router / gateways with cheap DNS Proxy software (i.e. incomplete or poorly programmed), there are lots of good ideas on what can go wrong if you are implementing DNS inspection on a firewall. For example: The EDNS packets are larger than 512 bytes. The default inspection on PIX/ASA V6/7 code was to force the 512 byte limit, which is now wrong. The default in ASA/PIX is to leave this option off, but if you have upgraded you can get some weirdness until you allow larger size DNS packets.