Speed of accessing web pages by dual-stack hosts and IPv4 single stack hosts

Can we say dual-stack hosts access web pages a bit slower than those hosts that ride on IPv4 only ? The answer is yes.

When browsing a website, dual stack hosts running Windows 7 will request AAAA record first and then follow by A record in the authoritative name server. In the case of IPv4 single stack hosts, only A record is queried. However, the difference should be 0.0x % and it should be hardly noticeable by users. To be fair, the extra query is necessary as dual-stack hosts take care of selecting IPv6 or IPv4 path to access a particular web server.  If both IPv4 and IPv6 paths can access the web site, IPv6 will always be selected first.


PACNET Sales 不知道 IPv6 是甚麼

PACNET 於去年三月宣佈推出全球 IPv6 服務。前幾天,我致電 Sales 想得報價單,Sales 竟然說不知 IPv6 是甚麽!我唯有回應,今時今日,如果做 ISP,連 IPv6 都不懂,不如早些結束這門生意吧。

及後致電另一家 ISP,Sales 說雖然公司已推出 IPv6 服務,但公司還未決定分配多少位址給專線用户。唉! APNIC 早有指引,每位專線用户可得 “/48” 的位址分配。

對於 IPv6 在香港的應用,我真的感到很悲哀。


DNSSEC Logging

Some time ago, I activated DNSSEC logging in my BIND.  The additional lines are as follows:

Guidelines can be found from DNSSEC_HOWTO at http://www.nlnetlabs.nl/publications/dnssec_howto/

I have allocated 2G for a large log.   I also need to pay attention to where the log file resides.  Since BIND operates under a chroot environment, the folder "/var/log/" actually means "/var/named/chroot/var/log".  This is a bit tricky.


Shame on Cisco

Cisco has sold thousands of IPv6 routers and networking equipment to ISPs and enterprises globally.  Yet, the web and email servers of Cisco are not IPv6-enabled.  If Cisco does not use IPv6, what sorts of negative messages it would give to the Internet community.

Shame on Cisco !!!


Gmail bans .exe file attachment

Gmail purposely blocks .exe file attachments as this is a common trick to spread virus, trojan and malware.  Not just only .exe, but other file types like ade, adp, bat, dll, msp, vb, sys, vbs, wsf are also prohibited.  Occasionally, I have to send .exe files to friends who are Gmail users.  I just rename the file to .pdf and attach in the email with the sha1sum of the .exe file before renaming.  On the other side, the recipient just download the attachment, rename it to .exe and then perform a sha1sum check.  Everything works quite well.

It seems not difficult to bypass Gmail's blocking of .exe files.  On the other hand, since Microsoft .exe files have the file signature of 4D5A in the header, I tend to think that it is possible for Gmail to screen out actual executable files instead of just looking at the name of the file extension.

Linux text-based browsers supporting IPv6

In my Linux box, I have been using lynx as a text-based browser for testing. Today, I tried elinks and w3m.  It is good to see all the three text-based browsers can access IPv6 websites.

Think it other way. Browsers should have no difficulty in supporting IPv6 websites.  The primary function of a browser is to display HTML, pictures and mutltimedia contents.  It is up to the OS itself to resolve host names to AAAA records and to reach the destination IPv6 address. What roles would browsers have in terms of IPv6 ?


".hotel" top level domain

Last year, when ICANN announced accepting applications for new generic top level domains, I knew for sure the ".hotel" top level domain would emerge quite soon. No need for me to mention that ".hotel" is extremely important for the hotel industry considering the large number of hotels worldwide. I am happy to know Affilias undertakes to manage the ".hotel" domain.

I am looking forward to seeing other useful and meaningful top level domains such as ".car" , ".bank", ".music" and probably ".nike" etc. My top interest is ".sex" which should be best used by websites with adult contents and pornographic materials. ".fuck" should not be allowed as this is explicitly an unpleasant name.  Stay tuned.


Why virtualization

Some friends have been asking why our organization need to go for virtualization ?  Is it because of Green IT or cost saving.  My answer is really simple.  We do not have enough rack space for individual servers.  Hong Kong is a place with very high rent. A sizable server room is unaffordable.


IT People's Silly English

Why IT people write this kind of clumsy silly English :

"The Android operating system software stack consists of Java applications running on a Java based object oriented application framework on top of Java core libraries running on a Dalvik virtual machine featuring JIT compilation."

After reading many times, I still can not figure out the relationship between individual components.


iPhone alarm clock

This is the 2011 new year  gift Apples offered to iPhone users.  All users were alarmed on 1 Jan 2011.