For those who spend time with DNS, they are likely to be aware of Bert Hubert’s PowerDNS which comes in two flavours, an authorative nameserver and a recursive nameserver

PowerDNS currently hard-codes the RD (recursion desired) bit to 0 when it sends DNS packets to nameservers configured in its forward-zones/forward-zones-file configuration parameter. This makes it impossible for one to configure an open recursive nameserver such as GPD as a forwarder. There is a ticket open in PowerDNS about it and Bert has mentioned on the mailing list that he is close to making the changes to provide the required functionality. Maybe this feature might come in a future PoweDNS recursor release

Thus domains which are repeatedly asked are answered from your local dnscache and the long tail of domains can be answered by GPD which may have its in its cache because what may be infrequent for your organisation is frequent for someone else who is using GPD thus giving you the best of both worlds. Fast local caching, and a fast recursive resolver when you have no locally cached results.

I’m assuming that in the coming weeks, Google will reach out to a number of organisations who use anycast DNS such as Content Delivery Network operators (Akamai, Limelight, CDNetworks etc) and authorative DNS servers operators (Dynect,UltraDNS,DNSMadeEasy etc) and work out better network routing amongst them.

These instructions assume that you have setup dnscache as an external forwarding cache for your organisation.
Then run the following commands (asssumes that you have installed dnscache as per DJB’s setup. Ubuntu/Debian users may have to adjust paths if they use packages from these distributions

echo 1 > /service/dnscache/env/FORWARDONLY
echo '8.8.8.8
8.8.4.4' > /service/dnscache/root/servers/@
svc -t /service/dnscache

I assume that you have enabled SSH access to the router so you can login via SSH and take backups of the old values of the upstream DNS

1. SSH into your router and run cat /tmp/resolv.dnsmasq . Save the IP addresses listed somewhere in case you want to revert back
2. Go to the Commands tab under Administration.
3. In the Commands box paste the following:

echo "nameserver 8.8.8.8
nameserver 8.8.4.4" > /tmp/resolv.dnsmasq
sleep 1
killall -HUP dnsmasq

4. Click Save Firewall (note: your WAN interface will be restarted)

Now, you can take advantage of the DNS caching on your router and misses on the routers DNS cache are sent to GPD for resolution. Note that websites which use CDN will now determine the closest node based on where the anycasted GPD addresses 8.8.8.8 and 8.8.4.4  resolve to relative to your network.

In a future post, I’ll write about how GPD can be integrated as an upstream forwarder using dnscache and why PowerDNS recursor doesn’t support using an open resolver as an upstream forwarder at present

In my opinion, Google wants to take advantage of the holiday season where everyone is visiting family and doing the usual “tech support”. A lot of early adopters would like to get their parents computer cleaned up and install alternative browsers. Google’s Chrome is clean and with the search box integrated nicely with the address bar would be very useful to many who don’t care about the lack of extensions.

I for one would really like for sites to actively discourage use of Internet Explorer 6 and push their users to alternatives such as Firefox, IE7, Chrome, Opera.

It will however be interesting to see how Chrome’s mechanism of being chatty with Google for its auto-suggestion may impact usage in markets where people have bandwidth limits.

Season 3 hasn’t disappointed so far and I had a great time watching Episode 3 with a brilliant moment when Moss recovers from his concussion and there is a Windows startup sound to signify his brain being “rebooted”

Adam is the co-founder and CTO of Velocix which was formerly known as CacheLogic.

Velocix is well known for its hybrid P2P based CDN network and I was trying to get a better understanding of how things worked behind the scenes in order to evaluate its suitability for various projects at work.

This is really oversimplifying their value proposition but for a technical person I would say that Velocix basically can provide a constant backfill to a BitTorrent swarm should a client want to use BitTorrent as a content delivery protocol.

Obviously Velocix can do a lot more than the above but it was hard for me to extract the above value proposition which was interesting to me from their website.

Hopefully this blog post can get some Google karma and help prospective Velocix customers

If you aren’t familiar with the browser, I would encourage you to visit Deb Richardson’s brilliant Field Guide to Firefox 3 which describes a number of key Firefox 3 features in a very accessible manner.

One thing I would like to mention is that Firefox 3 has improved connection parallelism. The default limit for concurrent connections per hostname has been increased from 2 to 6 which is similar to IE8. Details can be found in this bug report here and for the technically inclined these are the new defaults

pref(“network.http.max-connections”, 30);
pref(“network.http.max-connections-per-server”, 15);
pref(“network.http.max-persistent-connections-per-server”, 6);
pref(“network.http.max-persistent-connections-per-proxy”, 8);

Whilst the improved connection parallelism is one factor in improved page load performance, web server administrators who are currently serving content via Apache need to factor in increased concurrent connections from Firefox 3 and tweak their MaxClients setting appropiately.

If they are using Apache to serve static content, maybe they should consider switching to lighttpd and nginx for serving such content.

Google’s Steve Souder has a great roundup on Parallel Connections in this blog entry.

Depending on a third party long distance provider, it is actually cheaper to call up somebody and speak for a few minutes (HK-US charges are 7 cents/min and an SMS costs at minimum HK$ 2) and convey more than send a SMS to that person

Thus, I find Twitter’s SMS integration very useful. I tell my family members to sign up to Twitter and then also enable their mobile devices. In India, Twitter has a shortcode 5566511.

In HongKong, wifi access is very ubiquitous via the GovWiFi program as well as efforts by FON as well as PCCW, HongKong’s dominant telco provider so hopefully with the upcoming launch of the iPhone in Hong Kong it can help me by allowing me to have access to Twitter