« For the curious | Main | What I've been reading »
Where is Marginal Revolution?
The IP address for the NBER is http://66.251.72.129/. I'd like to know the IP address for Marginal Revolution but it's more complicated because MR is hosted by Typepad. Does anyone know if there is a numerical address for MR like that for the NBER? Please comment if you know it or can find it. Thanks in advance!
P.S. This for a classroom discussion of Domain Name Registrars that I am working on.
Posted by Alex Tabarrok on November 8, 2006 at 02:33 PM in Web/Tech | Permalink
Comments
204.9.178.60
It's easy to find. Just go to a command line and ping www.marginalrevolution.com and you'll see it. Or, for a slightly more direct answer, use nslookup or dig.
Posted by: Xellos at Nov 8, 2006 2:39:41 PM
I'm getting it as: 204.9.178.60 - but you're sharing that with other domains, so it points to your domain after passing the host header.
Posted by: lance at Nov 8, 2006 2:39:44 PM
I'll pipe up before someone more knowledgable comes along. I don't thik MR has its own IP address. The 204. address seems to be shared by all Typepad blogs (at least all the other ones I checked). So I'd guess that requests go to Typepad, which then directs visitors to the proper site on their servers. If you play the nice academic, you might be able to call up Typepad and have them tell you how they route things internally.
Posted by: ogged at Nov 8, 2006 2:50:14 PM
To followup on Xellos, to find out any address (assuming you're a Windows PC guy)
Open the start menu, click on "Run.."
Type 'cmd' in the box and hit OK. This should open up a black window. In this, type the following:
nslookup www.marginalrevolution.com
In the results, ignore the first part; the information you want is in the "Non-authoritative answer:" section.
Posted by: John at Nov 8, 2006 3:12:12 PM
Many domains are on shared IP addresses. So what's happening is that when you navigate to marginalrevolution.com, your browser sends a request to 204.9.178.60 and asks for pages from marginalrevolution.com and the server looks up which directory pages from marginalrevolution.com come from and sends back the page.
Posted by: don Hosek at Nov 8, 2006 3:17:22 PM
Right, I found 204.9.178.60 also but typing that into a browser will not get you to to MR the way typing in http://66.251.72.129/ gets you to the NBER that's why I'm asking for help to find the deeper address. I may have to ask Typepad.
Alex
Posted by: Alex Tabarrok at Nov 8, 2006 3:23:06 PM
A bit of a clarification: the domain "marginalrevolution.com" does not have an IP address; the address(es) are assigned to individual hosts (i.e., servers) within that domain. The domain itself is a purely abstract entity; you can only assign an address to an actual thing.
Thus, when you ask for the address for Marginal Revolutions, you probably actually mean the address of www.marginalrevolutions.com.
Note that it's common for an alias to be used, so that a DNS request for "marginalrevolutions.com" returns the address of the www... host. This is an important distinction, because if someone tries to send email to someguy@marginalrevolutions.com, the DNS request is going to ask for a different kind of record that may (and frequently does) yield an entirely different address.
Posted by: CWuestefeld at Nov 8, 2006 3:25:48 PM
The numerical address references a machine, not your site in particular. NBER is probably the only site on that machine, so it's configured to blindly send the site no matter what. Typepad has lots of sites crammed on a single machine, most likely. Since MR is shared with lots of other sites, that machine also uses the URL you used to figure out which site to display.
Posted by: John at Nov 8, 2006 3:26:31 PM
"Right, I found 204.9.178.60 also but typing that into a browser will not get you to to MR the way typing in http://66.251.72.129/ gets you to the NBER that's why I'm asking for help to find the deeper address"
As a poster said earlier, it is highly likely that hundreds, maybe thousands of domains resolve to 204.9.178.60. www.marginalrevolution.com is just one of them.
You're missing an extra piece of magic.... when somebody types the characters www.marginalrevolution.com into their browser, the browser does two things
Firstly, it figures out that it needs to talk to the machine living at 204.9.178.60. But there's a second step...
It doesn't just say to that computer: "give me the web page". It also tells it what it wants. In your case, it would say something like: "give me www.marginalrevolution.com/"
This is how the computer at the other end figures out which of the thousands of blogs to send to the browser.
Posted by: Richard G Brown at Nov 8, 2006 3:30:25 PM
Alex: there is no "deeper address". The address you see is the one the request is sent to. However, one of the very first things in that request is a specification of which HOST you're trying to talk to. Your web browser puts that HOST header in based on the address you type into the Address bar. When you just type the numerical "octets", the meaningful "marginalrevolutions.com" doesn't get stuffed in there. The server looks at this, and based on its value, decides which server to pretend to be.
The difference here is between physical and virtual servers. The IP address you got specifies a single physical server. But that box is acting as the server for any different web sites. The physical server receives all requests sent to that address, and by looking up the HOST value in a table, it decides which virtual server to hand the request off to.
Posted by: CWuestefeld at Nov 8, 2006 3:31:35 PM
The geek lurkers stumble out of our caves......
Posted by: John at Nov 8, 2006 3:36:47 PM
For more info about this, look up "virtual hosting", or "name based virtual hosting". Here's the Wikipedia entry on virtual hosting.
Posted by: Nathan Whitehead at Nov 8, 2006 3:41:12 PM
Thanks all. Alas, as I suspected, there is no one to one translation for a hosted website like MR so I can't quite use it as an example. I will stick with NBER.org.
Posted by: Alex Tabarrok at Nov 8, 2006 3:42:23 PM
although I should know this much better than I do, I believe you are concerning yourself only with the TCP/IP part of HTTP over TCP/IP.
The IP Address is the octets you mention, but the the HTTP request includes a GET request with Headers indicating the host name, address, querystring, etc.
Posted by: theCoach at Nov 8, 2006 3:46:43 PM
Think of the IP address (204,9,78.60) as something very similar to the adress of a building which can be a home or an apartment. Your browser is like a courrier. In both cases you are essentially telling your browser to go to the address and get the letter they have for me. In the case of the NBER, it sees the only door and gets the letter. In the case of MR it sees an apartment building and doesn't know which door is correct.
Posted by: nelsonal at Nov 8, 2006 3:59:09 PM
Alex, you should at least share the example with us now. Don't be a tease... curious minds await.
Posted by: Economister at Nov 8, 2006 4:10:57 PM
I don't want to nerd out to much, but typepad doesn't have a single "server" hosting 204.9.78.60, it has a single "pool" hosting it.
Posted by: Andrew at Nov 8, 2006 5:00:15 PM
www.dnsstuff.com is your friend:
http://www.dnsstuff.com/tools/lookup.ch?name=www.marginalrevolution.com&type=A
Here's what it tells me:
Searching for www.marginalrevolution.com A record at c.root-servers.net [192.33.4.12]: Got referral to K.GTLD-SERVERS.NET. (zone: com.) [took 25 ms]
Searching for www.marginalrevolution.com A record at K.GTLD-SERVERS.NET. [192.52.178.30]: Got referral to ns3.onlineaccess.net. (zone: marginalrevolution.com.) [took 10 ms]
Searching for www.marginalrevolution.com A record at ns3.onlineaccess.net. [63.85.86.50]: Got CNAME of marginalrevolution.blogs.com. and referral to i.root-servers.net [took 34 ms]
Searching for marginalrevolution.blogs.com A record at m.root-servers.net [202.12.27.33]: Got referral to D.GTLD-SERVERS.NET. (zone: com.) [took 99 ms]
Searching for marginalrevolution.blogs.com A record at D.GTLD-SERVERS.NET. [192.31.80.30]: Got referral to ns1.sixapart.com. (zone: blogs.com.) [took 83 ms]
Searching for marginalrevolution.blogs.com A record at ns1.sixapart.com. [204.9.178.9]: Reports marginalrevolution.blogs.com. [took 87 ms]
Answer: marginalrevolution.blogs.com. A IN 86400 204.9.178.60
So, the root DNS servers say to look at the DNS servers for ".com", the DNS servers for ".com" say to look at the DNS servers for "marginalrevolution.com", and the DNS servers for "marginalrevolution.com" say that "www.marginalrevolution.com" is a CNAME (an alias) for "marginalrevolution.blogs.com".
Having determined that the www.marginalrevolution.com record is a CNAME, the process starts over trying to track down an IP for the other name, "marginalrevolution.blogs.com". The IP address that is eventually reported (204.9.178.60) is properly understood to be the IP address of "marginalrevolution.blogs.com". And yes, as others have pointed out, there is some magic going on with "virtual host headers" at the web server layer that allows the web server to host multiple independent domain names on a single IP address, but that's not really related to DNS.
Posted by: Jeremy King at Nov 8, 2006 5:47:32 PM
I get this report from "dig":
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 15298
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;www.marginalrevolution.com. IN A
;; ANSWER SECTION:
www.marginalrevolution.com. 250 IN CNAME marginalrevolution.blogs.com.
marginalrevolution.blogs.com. 86350 IN A 204.9.178.60
www.marginalrevolution.com is a CNAME for marginalrevolution.blogs.com. A CNAME is an alias, and infinitely many CNAMEs can map to the same IP address. The main server at Typepad "sees" the CNAME that's used to get at it and internally routes to wherever "marginalrevolution" lives. (It's likely that it's just a bunch of database keys, and may not have its own standalone "site" with its own unique IP address).
More on CNAMEs
Posted by: Foobarista at Nov 8, 2006 6:04:52 PM
ilkka@rakkine:~$ whois 204.9.178.60
OrgName: SIX APART LTD
OrgID: SAL-48
Address: 548 Fourth St
City: San Francisco
StateProv: CA
PostalCode: 94107
Country: US
NetRange: 204.9.176.0 - 204.9.183.255
CIDR: 204.9.176.0/21
NetName: SIXAPART
NetHandle: NET-204-9-176-0-1
Parent: NET-204-0-0-0-0
NetType: Direct Assignment
NameServer: NS1.SIXAPART.COM
NameServer: NS2.SIXAPART.COM
Comment:
RegDate: 2005-11-01
Updated: 2006-02-01
RTechHandle: NOC2026-ARIN
RTechName: Network Operations Center
RTechPhone: +1-415-344-0056
RTechEmail: noc@sixapart.com
OrgTechHandle: PBW1-ARIN
OrgTechName: Wohlers, Peter B.
OrgTechPhone: +1-415-344-0056
OrgTechEmail: pwohlers@sixapart.com
# ARIN WHOIS database, last updated 2006-11-07 19:10
# Enter ? for additional hints on searching ARIN's WHOIS database.
Posted by: Ilkka at Nov 8, 2006 6:10:39 PM
The big blog aggregators like Typepad and Google use server farms with enormous databases, and use the CNAME of the blog name as the primary keys into the databases. They don't have separate servers for each blog.
Posted by: Foobarista at Nov 8, 2006 6:12:34 PM
Continuing the geekfest:
If you browse to the Netcraft report for that IP block, you'll see a big list of blog sites that share MR's IP address. (Just the first page has a bunch.)
That said, it's a misconception to think that all those sites live on one machine. The IP address could simply be the address of an Apache-fronted load-balancer. It's conceivable that MR could be hosted on a single box, or even multiple boxes in Typepad's server farm, where all the boxes have internal IP addresses. As I type this, I think that is the most likely scenario.
Posted by: Trieu Truong at Nov 9, 2006 1:06:02 AM
Correction:
It's conceivable that MR could be hosted on a single box, or even multiple boxes . . .
I meant that MR could still be hosted on a single, dedicated box, or even multiple boxes.
Posted by: Trieu Truong at Nov 9, 2006 1:12:58 AM
Let me recommend
http://www7.nationalacademies.org/cstb/pub_dns.html
as a balanced guide to the social/political/economic issues related to the DNS. (I spent at least 2 years working on this as a committee member, so I want to see it read!)
Posted by: Hal Varian at Nov 9, 2006 1:36:06 AM
癌症 抗癌中药 肿瘤 牛皮癣 白癜风 鱼鳞病 脂溢性皮炎 脂溢性脱发 斑秃脱发 湿疹 阴虱 带状疱疹 狐臭 青春痘 中国文秘网 皮肤病 皮肤病医药网 牛皮癣 脂溢性皮炎 斑秃 白癜风 鱼鳞病 脂溢性脱发 阴虱 生殖器疱疹 皮癣 湿疹 青春痘 螨虫 中国癌症网 健康 牛皮癣 白癜风 鱼鳞病 脂溢性皮炎 脂溢性脱发 斑秃脱发 湿疹 阴虱 带状疱疹 狐臭 青春痘
Posted by: iudagiu at Nov 9, 2006 4:17:03 AM
