I was asking this question to myself and my confusion was cleared only after buying arcade version of the xbox console.

Yes, you can play games from the disc without hard drive offline but cannot download games online and play it. Don’t forget that you will need a hard drive if you want to play older original xbox games.

Saving game progress doesn’t need hard drive since it can be saved with 256 mb memory unit which comes free with arcade version of the console. Just remember that out of 256mb, 120 mb is taken by system update files and about 10-50 mb used by each game save. So everytime you play a new game disc make sure you cleanup other game saves.

Playing music or videos can be done with usb drive instead of hard drive.

Don’t forget to use HDMl cable to connect your xbox to a HDTV for the best visual experience in terms of clarity and sharpness. This cable doesn’t come with arcade version and it has to be brought separately for about $20.

I just bought home a new Xbox 360, hooked up with my HDMI cable and the display worked perfectly. Then started the nightmare. I did a latest update with the console and display went blank and every time i started the 360 it gave “Display mode not supported” and there was no display. Even resetting the console (holding Y and RT) never worked for me no matter how many times i did resetting the console. I was using samsung 19” LCD TV with HDTV ready along with my Xbox.

I was very frustrated with this problem because initially the display worked at HDMI 1080p and now no display. My HDMI cable, Xbox were just everything fine after doing a thorough checkup. I had a weird feeling that update has got to do with the display problem.

I somehow fixed the problem by blindly playing with controller keys. Here is how you fix the problem to restore your display. Remember you have to do it blindly

Start Xbox and wait 1 min until it comes dashboard.
Press XBoX Guide button
Press RIGHT (2 times)
Press DOWN (4 times)
Press A (4 times)

Now you will be in display settings in xbox (blindly)

Press UP then A (see display comes back)

If there is no display..

Press UP then A (see if display comes up)

I got back my display back with UP and A second time and keep repeating the above step until you get the display.

I have seen this display issue with many people who done updates and hooked up with HDMI cable for Xbox. I hope this helps.

I love blackberry storm and recently i was having so much fun in touch screen typing the best part i like is typing especially using the SureType keyboard. From being a noob i learnt a lot of handy tips for typing in blackberry storm

In storm there are 3 types of keyboards.

1. SureType (portrait)
2. Multitap (portrait)
3. Full Keyboard (landscape)

I very much like typing in portrait mode, unlike in landscape where the tapping touch screen was hard in the corners with full keyboard. So, i handle pretty much everything in the portrait view. By default storm shows full keyboard in landscape view and suretype/multitap in portrait view.

Here are some of the useful tips you might want to know…

1. When you type in email address, just press SPACE to get @ symbol or SPACE to get a DOT.

2. To type all letters in caps, press and hold the SHIFT key (shown as ‘aA’) for 1 or 2 seconds and you will a padlock, which means all the letters you type will be in caps.

3. To type numbers continuosly, press and hold !?123 and soon it will be locked and then you can continuously type numbers or symbols.

4. You might want to get a DOT or full stop quickly when completing a sentence. To get this, press SPACE twice.

5. To type passwords or new words, use the Multitap Keyboard. To enable it, press main menu button select enable multitap.

6. When are you are typing a word in portrait mode using suretype and the predicted word shown on dropdown box just highlight it (dont tap the touch screen) and then ENTER key. In this way it would be easy for you to type fast.

7. To send/save something, say email or phone settings, just press main menu (it auto selects send or save) and again press main menu.

8. The very interesting part using suretype (in portrait view) is its ability to learn new unknown words. You need not switch to multitap.

For example to type `DIWALI`

Type `Di`
Type w, on dropdown just highlight `Diw`
Type a, on dropdrown highlight `Diwa`
Type l, on dropdown highlight `Diwal`
Type i, select `Diwali` and press ENTER

Thats it! Once the new word is learnt,

9. To type copyright © or trademark ® or language symbols

© -> Just place your finger (dont press) `C` key for 2 secs, you will see new button for ©

® -> Just place your finger and highlight R key for 2 seconds, you will see a new button appear on the screen. Tap it.

10. To make corrections or edit a word, place your finger on top of word and tap it, you will see a blue rectangular box, drag it to specific character and press BACKARROW key to delete characters or you can type continuously and you will get new word suggestions.

11. To make keyboard disappear or hide it, just slide your finger from top to bottom of keyboard to make it hide.

12. To quick insert your phone number or PIN while texting or emailing just type

`mynumber`
`mypin`

the phone will automatically insert your phone number and blackberry PIN to send to your friends.

Enjoy and have fun with your blackberry phone!

A must install application for every blackberry phone to search stores for applications, games and much more. Its FREE to download.

Gmail for Blackberry

Install gmail extended for your blackberry to directly send/receive gmail messages without web interface. It also has filter to block incoming messages. Its FREE to download.

Google Maps

Install google maps application on your blackberry for navigate using maps. It also supports GPS if your handheld supports it. Its FREE

Twitterberry

Twitterberry is a very useful blackberry application to post tweets and access timeline including private messages. It is FREE

Facebook

Connect to your friends with this facebook application for blackberry. It is so nice and compact.

Google Talk

Google Talk is an alternative instant messager to the one installed by default. If can easily chat with your friends list from gmail or orkut. It can be downloaded free from google mobile site.

Calls Blocker

A handy useful application to block unwanted incoming calls to your blackberry. It is a FREE application to download.

Opera Mini Browser

Opera is a popular browser for smartphones and mobiles. It can be installed as an alternative to the default browser in your blackberry.

Wordpress Mobile Plugin

A very useful wordpress plugin if you own a wordpress blog and want to do blog posts from your blackberry. Just install the plugin, set a mobile password and you can immediately post to your blog. It also supports google ad monetisation of your blog. Download FREE from the website.

eOffice

eOffice is a complete word processing package for your blackberry to compose/read doc, pdf or excel sheet documents. It also allows you to fax and print from your handheld. It is a commercial application for a small fee.

Color ID

A very interesting application worth taking a look. It lets you to customize LED indicator colors for SMS, email or incoming phone calls to specific color indication. It is FREE but to download you will need to have Appworld installed.

Screenshot

To capture screenshot on your blackberry phone, you will need this screenshot application.

I am not sure not many would realize that there is a major difference in touch screen working in both iphone and blackberry storm when comes to typing.

In Iphone, you have to just do a feather touch to type a character , while in case of blackberry storm you have to press down the whole touch screen (like a spring). Initially you will find bit different for whole touch screen to press down but once you get used to it it will be so easy to type fast.

In terms of display both touch screens show a high resolution images. I would definitely recommend blackberry if you are a business user or a person who likes to text a lot. For absolute fun iphone is the best!

Dont forget that blackberry storm is as good as iphone and much cheaper!

I recently bought blackberry storm 9530 and i am loving it with its gorgeous design, ease of use in texting with suretype. I was initially frustrated with no option of setting up email and there was only one option for blackberry enterprise email which i couldnt do it either.

With that being said, none of the google applications (gmail, google maps) refused to work as well. I frequently got “APN settings not specified” or “Tunnel failed” and the applications just hung up.

Solution

If you see no option for email setup, dont panic, just ask your mobile service provider to activate the blackberry internet and email service. I did contact vodafone by phone and within 20min or so every thing worked perfectly in my blackberry. Even third party applications worked like a charm. I guess every telecom mobile service provider must have some kind of activation for blackberry to work properly.

DNS (Domain name system) may not be known to most people who use internet but it is the real backbone and the invisible force driving the whole internet without which we would be seeing numbers and IPs. The whole meaning of domain names exist today just because of DNS.

INTRODUCTION

The simplest way of explaining DNS in one line is to map domain name to IP address. I am not sure how many would know that when somebody types a domain name in IE/firefox, the browser forwards the DNS request asking for ip address from the resolver of ISP (ISP Provider) and the resolver contacts the root servers and then systematically retrieves the IP address within a matter of few milliseconds.

Understanding DNS and its working is one of the most difficult computer engineering subject and yet most experienced network administrators struggle in this topic when it comes to DNS zone file writing.

Before i proceed with this article, the following are the MOST IMPORTANT points you should remember as otherwise you wouldnt understand bit.

POINTS TO REMEMBER

1. A Record must ALWAYS contain IP address (map host to IP)

When ever you specify A record it must contain IP address on the Right side. The A record is so important in DNS without which the meaning of mapping hostnames to IP would be absurd. So remember this!

2. CNAME (Alias) must contain hostnames. No IPs here

3. NS an MX records must contain host names. No IPs allowed.

4. Use the DOT in the end, whenever you specify a domain name in the DNS zone file. This DOT is so important and if you forget this you will have nightmares with your dns configuration.

For example

example.com. IN NS ns1.example.com.

why DOT? simply because it tells to start query from root servers (denoted by dot)

5. MX records (for mail servers) should contain hostnames NOT IPs.

COMMON DNS TERMS AND THEIR MEANINGS

(i) Glue Records

Glue records are A records that are associated with NS records to
provide “bootstrapping” information to the NS records nameserver. (see RFC 1912 section 2.3)

domain.com. IN NS ns1.domain.com.
domain.com. IN NS ns2.domain.com.

ns1 IN A 11.33.55.77
ns2 IN A 22.44.66.88

In the above example we are mapping each NS records to IP address (A record) thus binding nameservers to IP (that is glue them)

(ii) LAME Nameserver Delegation

A nameserver which gives non-authoritative answer is usually called ‘LAME’. Every domain must have atleast 2 nameservers and if i ask each of them, and if they have domain zone information, i will get authoritative answer. If not its a ‘lame delegation’. Refer to (see RFC 1912 section 2.8)

An example of lame delegation is

domain.com IN NS ns1.domain.com
domain.com IN NS ns2.example-server.net

ns1.domain.com is configured to have zone information about domain but ns2.exserver.net was not configured properly and does not have any information about the domain. So ns1 will answer authoritatively wheras ns2 wont which will be ‘lame’ until it is setup properly.

To get more in depth understanding, lets use dig tool for example.com

1. First we find the nameservers of example.com

dig example.com NS

;; ANSWER SECTION:
example.com. 158240 IN NS a.iana-servers.net.
example.com. 158240 IN NS b.iana-servers.net.

2. Since we have received 2 nameservers, we ask each of them whether they give authoritative answer. If its authoritative ‘aa’ flag in the header will be set in the answer received (’aa’ is authoritative answer)

> dig @b.iana-servers.net example.com NS
> dig @a.iana-servers.net example.com NS

;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 60896
;; flags: qr aa rd; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;example.com. IN NS

;; ANSWER SECTION:
example.com. 172800 IN NS a.iana-servers.net.
example.com. 172800 IN NS b.iana-servers.net.

Look in the flags

flags: qr aa rd

Since ‘aa’ is set in the answer, then both the nameservers of example.com provide authoritative answer. If it is lame delegation you wont get the authoritative answer.

CAUTION:

You should not use CNAME (alias) along with NS records and it often confuses most resolvers causing loops and often leads to ‘lame’ delegation.

domain.com. IN NS ns1.domain.com.
domain.com. IN NS ns2.domain.com.
domain.com. In CNAME ns9.example-server.net

So never use CNAME along with NS records.

(iii) Stealth Nameservers

Stealth Nameservers (or hidden nameservers) are mismatched/conflicting nameservers which exist at root level against of nameservers in the domain.

To illustrate this, when i ask parent servers about your domain for NS records at root level i get

ns0.domain.com
ns2.domain.com
ns3.domain.com

but when i query nameservers of your domain for the NS records are not the same and comes like

ns0.domain.com
ns2.domain.com
ns.example-dns.net

Since ns.example-dns.net and ns3.domain.com is hidden both are a ’stealth nameservers’. Although there is nothing wrong in it, it is advisable not to have any stealth nameservers both at root level and in your dns server.

You can use dig command to lookup NS records at root server level.

dig +trace @K.root-servers.net example.com NS

and to ask one of the nameservers of the domain

dig @ns0.domain.com example.com NS

Look for any NS mismatch between the two queries. If there is a nameserver missing at root level, add the missing nameserver to your domain registrar. If the nameserver missing at domain level, add the nameserver to the zone file of the domain and update all your secondary nameservers.

(iv) Open DNS Server

Running the dns server ‘open’ is a big security risk since it answers recursive queries both from inside and outside your network. It means anyone can query your server for IP address and your dns server will answer them.

To illustrate this, we have two nameservers running bind for domain example.com

ns1.example.com
ns2.example.com

We ask ns1.example to resolve outside domain google.com and if we get IP address (A record) in the answer section, then it means it is an ‘open dns server’

dig @ns1.example.com google.com
dig @ns2.example.com google.com

;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 12107
;; flags: qr rd; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;google.com. IN A

;; Query time: 32 msec

Since there is no ANSWER section or IP address both the nameservers does not constitute open dns server.

If you happen to run bind8 or later, all you have to do is set ‘recursion no’ within options to disable dns server answering recursive queries.

options {
....
recursion no;
}

(v) Zone Transfers (AXFR request)

Zone transfers are done by secondary nameservers to retrieve latest and updated zone information for domain from master or primary nameserver. Zone transfers should only be made available to secondary nameservers and not to the open world as it is a big security risk and may expose the internals of your network to the attacker.

To request a zone transfer for example.com we need to ask the master nameserver first. See the below example with dig.

dig @ns1.example.com example.com

If you see the output with full zone file, then you have to disable the zone transfer. In most cases you will see connection failed or REFUSED which means zone transfer is not allowed and its a good thing.

COMMON DNS ERRORS IN ZONE FILE WRITING

1.No CNAME pointing to NS records

domain.com. IN NS ns1.domain.com.
domain.com. IN NS ns2.domain.com.
domain.com. In CNAME ns9.example-server.net -----> WRONG

Placing CNAME along with NS the all of namservers will fail and will result in lame delegation. Dont do that!

Refer to RFC1912 2.4 and RFC2181 10.3

http://tools.ietf.org/html/rfc2181
http://tools.ietf.org/html/rfc1912

2. Avoid running DNS servers on IPs on same subnet (/24) or on same server.

The whole purpose of DNS is for nameservers to be spread over different geographical locations so that if one dns fails the other would work. Although it is very common practice to run both nameservers on same server or subnet, it would not provide fault tolerance. If the server fails your nameservers will fail and your site wont load.

ns1 IN A 75.33.22.xx -----> same subnet /24
ns2 IN A 75.33.22.xx -----> same subnet /24


3.Proper GLUE

Always add glue to your NS records to the IP addresses using A record, failing which one of your nameservers will fail.

domain.com. IN NS ns1.domain.com.
domain.com. IN NS ns2.domain.com.

ns1 IN A 1.2.3.4 —–> GLUE
ns2 IN A 2.4.6.9 —–> GLUE

Refer to RFC1912: http://tools.ietf.org/html/rfc1912

4. No duplicate MX records

domain.com. IN MX mail.domain.com.
domain.com. IN MX mail.domain.com —-> DUPLICATE

5. Allow Port 53 for both UDP and TCP connections

If you use firewall make sure you do not block port 53 for DNS tcp and udp requests. By default dns lookups use UDP protocol while zone transfers and notifications use TCP protocol of port 53.

Port 53 UDP = Dns Requests
Port 53 TCP = Zone transfers

6.CNAMEs cannot co-xist with MX hosts.

Do not specify CNAME or aliases pointing to MX records.

domain.com. IN MX 10 mail.domain.com.
mail IN CNAME domain.com. ----------> WRONG

Instead use A record to map directly to IP address

mail IN A 11.33.55.77 ---> CORRECT

Refer to RFC1912 http://tools.ietf.org/html/rfc1912

7. MX Records should not contain IP addresses.

domain.com. IN 10 MX mail.domain.com. ----> CORRECT
domain.com. IN 20 MX 11.22.33.44 -----> WRONG

The correct way of doing this is glue the mx host to A record.

domain.com. IN MX 10 mail.domain.com. -----> CORRECT
mail IN A 11.33.55.77 ----------> CORRECT


8. NS records should NOT contain IP address

Always specify nameservers for your domain with NS records. It should be a name and not ip addresss

domain.com. IN NS dns0.domain.com. —–> CORRECT
domain.com. IN NS 75.xx.xx.xx ———–> WRONG

REVERSE DNS FOR MAIL DELIVERY

For proper mail delivery, the following anti-spam methos are very important to make sure the email is delivered to users inbox. Most public email service providers yahoo, hotmail and gmail do use these parameters to flag email is spam or not.

(i) Setup Reverse IP for your mail server with PTR in DNS (needs Dedicated IP)
(ii) Setup SPF Record in your DNS
(iii) Setup Domain Keys

I have seen on many occasions if you use shared hosting plan, most emails do land up in spam/bulk folder in the users inbox. So use a dedicated server

8. Setup reverse IPs for Mailserver IPs

In order to setup reverse IP, first you will need to place a request to your hosting provider (since they own Ip address) and ask them to setup a reverse IP to your mail server. Once that is done you have to place a line using PTR in your domain zone file.

To test reverse ip lookup

host

will show the output of reverse dns.

9. Setup SPF record

SPF record is setup using TXT record in your dns zone file. It looks like what is shown below. Visit http://openspf.org for more information about setup and configuration.

domain.com. IN TXT “v=spf1 a mx ip4:11.33.55.77 -all”

To query SPF record using dig

dig domain.com TXT

10. Domain Keys

Domain keys is an authentication framework to digitally sign the email using public keys to prove email originating from partiular domain and not from a phishing or spam site. More information can be found http://domainkeys.sourceforge.net/

It basically contains 2 records (with and without selector) placed under TXT using underscore along with generated public key.

sel_domainkey.example.com IN TXT (with selector)
_domainkey.example.com IN TXT (without selector)

The ’sel’ is a selector and can be selector name.

Once you setup domain keys you will see signed by in the mail header on every smtp email you send.

How to setup nameservers for your domain using BIND9

You can setup dns nameservers for your domain if you have VPS or dedicated server just from command line. You dont need a control panel or webbased interface to do this.

yum install bind

(1)
open /etc/named.conf, add the following lines…

zone “domain.com” {
type master;
file “/var/named/domain.com.com.db”;
};

(2)
create a file under /var/named/domain.com.db (replace example.com to your domain)

nano /var/named/domain.com.db

and paste the full sample bind zone (see below replacing domain.com to your domain)

Make sure you…

(a) have 2 ip addresses
(b) replace domain.com to your domain.
(c) change the ip addresses whereever xx.xx.xx.xx is present
(d) increment the serial last 2 digits by one for every change to the file
(e) dont forget the DOT at the end of domain

(3) Save changes to the file and restart bind.

service named restart

(4) Go to your domain registrar, register the new nameservers with 2 ips, then update the nameservers for your domain.

Visit http://intodns.com to check for any dns errors or you may use DIG tool to fix dns problems.

;=================================================================
;SAMPLE BIND DNS Zone FILE
;for ANY Domain (Just change domain.com to your site)
;================================================================

; Before you start DONT FORGET THE DOT AND SERIAL INCREMENT

$TTL 14400
$ORIGIN domain.com.

; SOA Record
; Specify Primary nameserver ns1.domain.com
; Serial should increment every update
@ 14400 IN SOA ns1.domain.com. webmaster.domain.com. (
2009092902 ; Serial in YYYYMMDDXX (XX is increment)
10800; refresh seconds
3600; retry
604800; expire
38400; minimum
);
; Website IP Address specified in A record

IN A xx.xx.xx.xx

; Minimum 2 DNS nameserver names

IN NS ns1.domain.com.
IN NS ns2.domain.com.

; Mapping all Nameservers and their corresponding IPs (GLUE)

ns1 IN A xx.xx.xx.xx
ns2 IN A xx.xx.xx.xx

; Specify any subdomains and www entry here using CNAME record

www IN CNAME domain.com.
ftp IN CNAME domain.com.
server IN CNAME domain.com.
webmail IN CNAME domain.com.

; Setup MX record (mail exchanger with priority)
domain.com. IN MX 10 mail.domain.com.

; set A record for mail
mail IN A xx.xx.xx.xx

Enjoy DNS!

I have been quite intrigued with the working of these URL shortner scripts and surprisingly most of them
employ an ingenious solution to compress the URL to a shortened one.

http://example.com/fe45 ——-> http://corpocrat.com/blah/page.htm

The answer is base36 encoding. why base36? because it can contain 26 alphabets and 10 numbers in the output. This is surprisingly simple way of encoding a URL.

Base 36 is nothing but, you keep on dividing a number by 36, collect its reminders (or modulo) and map them to the corresponding table of alphabets and numbers. see base 36 table.

This is how most URL shortner scripts work…

1. First Insert a long URL into the database. Get the id of row which should be a primary key and unique. In most cases it can also be auto increment.

URLs are stored in database with unique id.


-----------------------------------------------
ID URL
-----------------------------------------------
10099 http://corpocrat.com/
14566 http://corpocrat.com/blah/page.htm


2. Now get the corresponding ID to that URL stored in database. Since the ID it can contain only numbers 0-9 (base 10), convert to base 36 using php function base_convert from 10 to 36

<?php
    $id = "10099";
    echo base_convert($id,10,36);
?>

Output:

1099 ——-> uj
10099 ——> 7sj
100099 —–> 258j

As you see the output produced by base36, smaller numbers output fewer characters and for even millionth number, we generate just 4 characters in length in the form of mixed alphabets and numbers.

3. Store that base36 output in the database, respective to that of ID in a separate field. so the trimmed version of URL becomes….

http://example.com/7sj

for the URL http://corpocrat.com with ID 10099 stored in the database.

The above http://example.com/7sj is a mod-write for the php page

http://example.com/7sj -----> http://example.com/short.php?baseid=7sj

which queries the database based for destination URL against base38 stored and then redirects.

The above is a very simple technique and besides this there are many more techniques for URL shortening, for which i recommend the below referenced resources.

Enjoy!

Useful References

* URL compression for huge set of URLs in GB sizes - http://anres.cpe.ku.ac.th….ncsec.pdf
* URL shortening hashes - http://www.codinghorror.com/blog/archives/000935.html

Note: Base 64 can also give wide range of characters in url shortening.

In many cases, you might want to check whether an ip address falls under a same subnet or not. It can be done both in perl and php using the Network library.

For PHP use Net IP4 library
For PERL use Net::IP library

<?php
// check for IP falls in same subnet or not
include("Net/IPv4.php");

$objIP = new Net_IPv4();

echo $objIP->ipInNetwork("192.xx.xx.xx", "192.xx.xx.x/24") ? "Same Subnet" : "Outside the Subnet";
?>

In perl you can use Net::IP module

#!/usr/bin/perl

use NetAddr::IP;

my $netwrk  = NetAddr::IP->new('192.xx.xx.x/24');
my $ip = '192.x.x.x';

if ($ip->within($netwrk)) {
    print "IP is in same subnet";
} else {
    print "IP outside the subnet";

   }

I a wrote a dns checking script perl in script (CGI available) which can perform various tests for dns including…

* Checking for Nameservers NS records
* Website IP address (A Record)
* NS records from parent servers (root server)
* Check for LAME nameservers (Authoritative nameservers)
* Check for Open DNS server
* Check for Zone Transfer (AXFR)
* Check for NS ips on same subnet
* Check for SOA record (with TTL, Referesh etc…)
* Check for Stealth Nameservers
* CNAME Misconfiguration.
* Mailserver MX records
* MX Reverse IP Retrieval
* Check for SPF record
* Check for Domain Keys

The reason i chose perl over php is because its simply too powerful when programming for DNS. You can download the CGI version of script written in perl below.

Download: dns-test.zip
Documentation: see here

Requirements

Linux
Perl
Net::DNS
Net::Version
Net::IP