Tuesday, September 28, 2004
Overly pendantic commands
I was called by R (guy I work for) to double check the email system since it looked like (to him) that it wasn't working at all and no emails were being sent (order confirmations, etc). I start checking, and from what I could tell, the email system was working fine. I placed a few test orders from a few sites and got the confirmation email. And from the mail logs, it looked like it was sent off to R as well.
But he wasn't getting them.
A few more tests while talking to R seemed to confirm that email sent to him from the server was being accepted by his ISP, but R was still not getting them. Which indicates to me that his ISP is filtering out spam and for whatever reason, email from this server was being flagged as spam and not delivered.
I then did the following on the server to check something out:
[root]rnm.miami:~>hostx -t mx XXXXXXXXXXXX XXXXXXXXXXXX MX 20 mail2.XXXXXXXXXXXX !!! XXXXXXXXXXXX MX host mail2.XXXXXXXXXXXX is not canonical XXXXXXXXXXXX MX 10 mail.XXXXXXXXXXXX !!! XXXXXXXXXXXX MX host mail.XXXXXXXXXXXX is not canonical
Hmmm … odd. Double check the zone file.
$TTL 3600 @ IN SOA ns1.XXXXXXXXXXXX. root.XXXXXXXXXXXX. ( 2004091801 ; Serial 10800 ; Refresh 3600 ; Retry 3600000 ; Expire 3600 ) ; Minimum IN NS ns1 IN NS ns2 IN NS ns3 IN MX 10 mail IN MX 20 mail2 mail IN A XXX.XXX.XXX.XXX mail2 IN A XXX.XXX.XXX.XXX ns1 IN A XXX.XXX.XXX.XXX ns2 IN A XXX.XXX.XXX.XXX ns3 IN A XXX.XXX.XXX.XXX
Nothing out of the ordinary. The RRs for mail and mail2 aren't
CNAMEs (which is a common mistake). They look fine to me, and
running host on outside machines report back fine:
[root]linus:~>host -t mx XXXXXXXXXXXX XXXXXXXXXXXX MX 20 mail2.XXXXXXXXXXXX XXXXXXXXXXXX MX 10 mail.XXXXXXXXXXXX
A quick Google
didn't reveal anything I already didn't know (most of the problems I found
were CNAME errors). So, I started playing around with the zone
file. Make a change, same error. Make another change, same error. It was
only when I removed all references to mail and
mail2 when I discovered the problem.
By then, I was doing hostx -G -S -C -A -L 1 zone
(which verifies the entire zone) and getting back errors about
mail and mail2. Which shouldn't be happening, as
I had just removed all references to them in the zone file. There
was only one other place where they were defined—/etc/hosts.
Once I removed those entries from /etc/hosts, the problem went
away:
[root]rnm.miami:~>hostx -t mx XXXXXXXXXXXX XXXXXXXXXXXX MX 20 mail2.XXXXXXXXXXXX XXXXXXXXXXXX MX 10 mail.XXXXXXXXXXXX
Talk about your overly pendantic host command.
We Americans and our silly love affair with the car
The fact is, public transportation is an absolute failure everywhere it has been tried except for cities which grew up around a public transportation network in the pre-automobile era. Public transportation—and I am second to none in my love for public transportation, and have a fabulous commute besides—is more expensive, both in money and environmental costs, than automobiles outside of New York, Boston, San Francisco, Philadelphia, and Chicago. That's right, I said it's more environmentally costly than giving every person on the train a car, because a train running empty consumes an enormous amount of energy.
In order to persuade people to live in a public transit zone, rather than an auto zone, the trains have to run frequently enough, and for a long enough period, for people to be able to base their lives around them. Those five cities (and I'm not sure about Philly) produce net energy gains only because they shift an enormous number of people during rush hour; enough to offset the inevitable losses during off peak periods, when the trains expend a tremendous amount of energy to move very few people. If your trains aren't jam packed for six hours a day during rush periods, you can never make up the losses.
Via Marginal Revolution, Jane Galt: This will drive the environmentalists crazy
Public transportation certainly fails here in Lower Sheol. We have one light rail system that runs north/south through three counties, which is great if you live say, within a mile or so of one of the stations. But the rail was first laid decades ago when the population was primarily living within a few miles of the coast (and back then, the rail was mostly used for bulk cargo and passenger trains from up north). Now, the bulk of the population has spread westward, meaning you have to use a car to drive to the station, or take other forms of public transportation to get to the rail system.
I've taken the bus. Three times since that was written; the third time was several years ago when a bunch of us decided to head on down to the Miami Metro Zoo. We took Tri-Rail, the light rail system mentioned above (and we all drove to the station, which says something right there) down to Metrorail (an elevated tail system in Miami) to the Metromover to Metrobus to the Miami Metro Zoo.
What would have taken us about 40 minutes by car turned into a three hour trek. Now, it wasn't a bad treck; nothing bad happened on the way down there, or the way back, and it certainly was nice not having to think about parking. But we did have to worry about missing one of four different modes of public transportation, and it did take a significantly longer time to reach our destination. And we probably spent as much money taking public transportation as it would have cost us in gas and parking fees, so it was mostly a wash except for the time.
Jane Galt also links to this interesting article from the New York Times:
Sprawl is scarring the American landscape. If by “landscape” you mean the pasture or forest near your home that has been paved, then sprawl does look like an abomination. Who wouldn't prefer to be surrounded by greenery, especially when you're not paying property taxes for it?
But if you look at the big picture, America is not paving paradise. More than 90 percent of the continental United States is still open space and farmland. The major change in land use in recent decades has been the gain of 70 million acres of wilderness—more than all the land currently occupied by cities, suburbs and exurbs, according to Peter Huber, author of Hard Green: Saving the Environment From the Environmentalists. Because agriculture has become so efficient, farmers have abandoned vast tracts of land that have reverted to nature, and rural areas have lost population as young people migrate to cities. You may not like the new homes being built for them at the edge of your town, but if preserving large ecosystems and wildlife habitat is your priority, better to concentrate people in the suburbs and exurbs rather than scatter them in the remote countryside.
Via Jane Galt, The Autonomist Manifesto (Or, How I Learned to Stop Worrying and Love the Road)
A long article, but worth reading. It mentions several novel ideas traffic engineers are working on to relieve congestion, including variable toll roads (where the toll varies by how much traffic is currently on it) to systems to help cars drive themselves down highways.
