Safari connectivity and Security Update 2004-09-30 (and OS Updates in general)

A number of times over the past four to six months, we've published user reports of Safari connectivity problems after installing an OS update. In each case, these reports describe issues where Safari can't connect to some sites on the first try, but (for most users) will eventually load the desired page after several tries. Our most recent such report, yesterday, was the result of a significant number of people who have experienced this problem -- coincidentally or not -- after installing Security Update 2004-09-30.

As we previously stated, Security Update 2004-09-30 was a relatively minor update in terms of the number of files replaced; specifically, the Update only changed files relating to NetInfo Manager, File Sharing, QuickTime, postfix, and cupsd. None of these files should affect Safari connectivity. (Similarly, in many of the previous cases where users reported these problems after installing an update, that update should not have affected Safari.) In addition, whenever we post such reader reports, we inevitably get a number of messages from other readers stating that they had the problem before installing the update or are currently experiencing the problem even though they haven't installed the update. So there's no clear link between such updates and these problems (and, technically, we can find no obvious link, given the files installed by the update).

However, the fact of the matter is that we've seen an enormous increase in the frequency of these reports since the release of Security Update 2004-09-30 -- too many for it to be just a coincidence. In the past 24 hours, for example, we've received well over 100 messages describing similar Safari connectivity issues, nearly all of them noting that the problem only started after installing this particular Security Update. There are also many similar reports on message boards, forums, and mailing lists around the 'net.

Frankly, we're stumped at the moment. Although the Security Update shouldn't be affecting Safari connectivity, the two seem to be highly correlated, if not explicitly related by cause/effect. As a result, we've been combing through reader mail trying to find any patterns or details that might help narrow down the true nature of this issue.

One thing that does stand out when reading these reports is the common behavior of these connectivity issues. In nearly all cases, Safari cannot reach a particular site or sites on the first try, but subsequent tries will eventually produce a successful connection. In our experience, this type of behavior most commonly occurs when the OS is having DNS (domain name system) problems. (All servers on the Internet have a dedicated IP address, which is how your computer connects to them to request data, such as a Web page. The DNS system is what allows you to type in "cnn.com" instead of the CNN server's actual IP address -- a DNS server converts "cnn.com" into 64.236.16.84, or whatever the actual IP address might be.) When a DNS problem occurs, your computer cannot properly translate website domain names into the appropriate IP address, so you get an error.

Comments from readers seem to support a DNS-related problem (see the DNS-related suggestions below). Reader Joe Foley writes, "Safari fails to connect on the first try about 50% of the time but (so far) is successful on the second try 100% of the time using the reload button...It seems to be a more frequent problem with the first page from a site. Linked pages on the same site may be more likely to open on the first try." This behavior is consistent with DNS hiccups -- once your computer successfully connects to a DNS server to associate a particular IP address with a domain name, subsequent requests to that domain should also be successful (at least until Safari needs to query the DNS server again).

Suggested causes/solutions Readers have presented a number of theories and suggestions to try to explain this issue, or at least to try to work around it:

Safari DNS cache? What is especially peculiar about this issue (besides the fact that it seems to occur so frequently after installing an OS update) is that whereas DNS problems usually affect all Internet clients -- Web browsers, email clients, streaming audio software, etc. -- for most users, this problem seems to affect only Safari. Indeed, many readers report that switching to another browser, such as Firefox or OmniWeb, allows them to load the affected site(s). Reader Allan Doyle suggests an explanation:

"I have noticed that Safari seems to have an internal DNS cache that is slow to update because when I do DNS changes on my web servers I have to restart Safari to get it to see the new sites even after I get the new DNS info in a terminal session using 'host'."

If this is the case, the workaround (quitting Safari each time it happens) would seem to be a significant hassle, given how frequently those experiencing this problem see it.

[Note that not all users are seeing this issue only with Safari; several MacFixIt readers have reported that it also affects Firefox and Netscape. However, these readers are in the minority.]

Manually entering DNS addresses Steven Smith suggests a different approach: If you're using a DHCP connection through your ISP, manually enter your ISPs DNS server IP address(es) in the Network preferences pane of System Preferences. (When using DHCP, this information is generally supplied by your ISP's DHCP server.) The downside to this workaround is that if your ISP's DNS servers ever change, you'll need to manually update those addresses.

[As a side note, one of the first explanations we considered was that perhaps certain ISPs were having DNS issues: Perhaps, in the case of Security Update 2004-09-30, several of the main DNS routers on the 'net started behaving erratically at approximately the same time Apple released the update. However, that wouldn't seem to explain why this issue mainly affects Safari, and it also wouldn't explain why some users with multiple computers see the issue on one computer but not on another. For example, Richard Pockat writes, "I have noticed this to an annoying extent on one machine and little or none on another. The first machine is a 2Ghz Dual, the second an original flat screen iMac. Both were updated with software update."]

Trailing slash related? For MacFixIt reader Tom Burke, the issue only occurs when he types in a URL without a trailing slash: "I have the same problem. It happens when a URL has a backslash at the end. If you delete the backslash, the page will load. I never realized how often URLs had the backslash at the end." In other words, typing a URL as "www.cnn.com/" won't work, but "www.cnn.com" will.

Incomplete URLs related? Reader Wayne Rugenstein reports that the issue is especially common when he simply types a website's domain without the leading "www" or trailing "net/com/org/etc":

"I am having the same connection issue with Safari after installing the latest security update, getting the 'Can't find x server' error message. This is especially happening when I just type in the name of a website without using the 'www.' and '.com' part of an address. If I try to go to MacFixit for example I would normally just type in 'macfixit' in my URL address line and hit return and let Safari add the 'http://www.' and '.com' part, but now I usually need to type this out as well for it to work properly."

As we have never experienced this issue in-house here at MacFixIt, we can't verify any of these theories or suggested workarounds. We would appreciate feedback from readers as to their effectiveness. Drop us an email at Late-breakers@macfixit.com.

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