Mac Software Update Not Working – Solution

Recently a lot of Mac users are complaining that the software update program is not working correctly and I also ran into this issue today. It just tells you “your software is up to date” but obviously there’s some software not up to date. For example, I opened iTunes and it told me there’s a newer version of iTunes, would you download it? I clicked “download” and the software update app opens but it told me that there’s no update – that made me crazy.

I was not alone. Someone already complained in apple’s support forum. I looked through the replies but found nothing that worked, including deleting com.apple.SoftwareUpdate.plist files. After investigating the problem for minutes, I found that the software update app downloads information from swcdn.apple.com, but the resolved IP for me is not working – as it’s CDN, users at different locations may get different IP addresses.

The solution is simple – add the following line to your /etc/hosts file:

80.67.74.160 swcdn.apple.com

and go back to check software update.

For readers interested in the details, here is the dig result on my machine:

$ dig swcdn.apple.com

; <<>> DiG 9.6.0-APPLE-P2 <<>> swcdn.apple.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 18722
;; flags: qr rd ra; QUERY: 1, ANSWER: 5, AUTHORITY: 2, ADDITIONAL: 2

;; QUESTION SECTION:
;swcdn.apple.com.       IN  A

;; ANSWER SECTION:
swcdn.apple.com.    1178    IN  CNAME   swcdn.apple.com.akadns.net.
swcdn.apple.com.akadns.net. 279 IN  CNAME   swcdn.apple.com.edgesuite.net.
swcdn.apple.com.edgesuite.net. 19178 IN CNAME   swcdn.apple.com.edgesuite.net.globalredir.akadns.net.
swcdn.apple.com.edgesuite.net.globalredir.akadns.net. 279 IN CNAME a1562.ce.w.ytcdn.net.
a1562.ce.w.ytcdn.net.   1179    IN  A   74.63.75.122

;; AUTHORITY SECTION:
ytcdn.net.      59910   IN  NS  dns6.expirenotification.com.
ytcdn.net.      59910   IN  NS  dns5.expirenotification.com.

;; ADDITIONAL SECTION:
dns5.expirenotification.com. 2803 IN    A   67.159.44.159
dns6.expirenotification.com. 377 IN A   67.159.44.159

;; Query time: 6 msec
;; SERVER: 124.207.160.106#53(124.207.160.106)
;; WHEN: Sat May 15 23:33:33 2010
;; MSG SIZE  rcvd: 305

So ytcdn.net might be an expired domain! Look at its whois information:

Domain Name: ytcdn.net

Registrar: XIN NET TECHNOLOGY CORPORATION
Whois Server: whois.paycenter.com.cn
Referral URL: http://www.xinnet.com
Status: clientUpdateProhibited

Expiration Date: 2011-04-30
Creation Date: 2008-04-30
Last Update Date: 2010-05-01

Name Servers:
    dns5.expirenotification.com
    dns6.expirenotification.com
See ytcdn.net DNS Records

Information Updated: Sat, 15 May 2010 15:40:22 UTC

Notice that most complaints of software update started in May... I don't know the relationship between ytcdn.net and Akamai CDN, but if ytcdn.net is really expired, it is a serious fault. Apple is using Akamai as its CDN, and Akamai redirects some users to ytcdn.net. As I know, most of these users are in China, but some users in other countries are also affected.

Apple, please contact your CDN provider to solve this problem.