Root servers - Revision history

Jimbo at 19:22, 21 May 2006

2006-05-21T19:22:14Z

Jimbo: I have officially been up too long now.

2006-05-21T06:17:20Z

I have officially been up too long now.

Jimbo at 06:12, 21 May 2006

2006-05-21T06:12:31Z

Jimbo at 05:56, 21 May 2006

2006-05-21T05:56:55Z

Jimbo at 05:54, 21 May 2006

2006-05-21T05:54:35Z

Jimbo at 05:53, 21 May 2006

2006-05-21T05:53:56Z

Jimbo at 05:41, 21 May 2006

2006-05-21T05:41:40Z

Jimbo: omg pretty colors

2006-05-21T05:27:05Z

omg pretty colors

New page

The '''root servers''' are the top tier of nameservers which contain the necessary information to resolve each of the [[top level domains]] of the internet. There are currently several clusters of root servers. Within each cluster, the member servers are spread out geographically both to minimize [[latency]] and to maximize [[fault tolerance]] for the internet as a whole. The separate clusters service separate [[top level domains]]; if you initially query a root server which is not a member of the proper cluster it will give you the IP address of a server in the correct cluster.

Once given this address, you repeat your query to that server. If you are still not in the right cluster to provide [[authoritative nameserver|authoritative]] answers for the [[top level domain]], you will be forwarded again, and repeat your query again. Once you arrive at the [[authoritative nameserver]] for your top level domain, you repeat your query to it, and it will point you to the authoritative nameserver for the second level domain. This process can continue once or more for every subdomain level of the URL you wish to resolve.

For example, when you visited www.freebsdwiki.net, either your own nameserver or your ISP's nameserver had to first resolve the [[DNS record types|A record]] to an IP address, beginning from the '''root servers''' and working its way downward, repeating the same query to progressively lower-hierarchy servers until it got its final answer. That process, were you to repeat it on the command line with the DNS tool [[dig]], would have looked much like this:

workstation# '''dig @a.root-servers.net www.freebsdwiki.net'''
;; ->>HEADER<<- QUERY: 1, status: NOERROR, '''ANSWER: 0''', AUTHORITY: 13, ADDITIONAL: 14
;; AUTHORITY SECTION: NS A.GTLD-SERVERS.net.
;; ADDITIONAL SECTION: A.GTLD-SERVERS.net. 172800 IN A 192.5.6.30

workstation# '''dig @a.gtld-servers.net www.freebsdwiki.net'''
;; ->>HEADER<<- QUERY: 1, status: NOERROR, '''ANSWER: 0''', AUTHORITY: 2, ADDITIONAL: 2
;; AUTHORITY SECTION: NS ns1.jrssystems.net.
;; ADDITIONAL SECTION: ns1.jrssystems.net. 172800 IN A 66.154.114.98

workstation# '''dig @ns1.jrssystems.net www.freebsdwiki.net'''
;; ->>HEADER<<- QUERY: 1, status: NOERROR, '''ANSWER: 1''', AUTHORITY: 2, ADDITIONAL: 2
''';; ANSWER SECTION: www.freebsdwiki.net. 300 IN A 66.154.114.98'''

Basically, it went like this: first you asked a.root-servers.net (after finding its IP from your own root hint file) where to find freebsdwiki.net. It didn't know the answer, but it did know you should be asking one of the gtld-servers about the .net TLD - so it told you that it knew an NS (nameserver record) for the gtld-servers. And since it figured you would just come right back and pester it for directions to that NS record, it went ahead and gave you the corresponding IN A (internet-class A record), which contained its actual IP address, before you specifically asked for it.

So then you asked a.gtld-servers.net, but it didn't know the answer either. However, it did know the authoritative nameserver for the ''second'' level domain freebsdwiki.net - so it told you to go ask the NS ns1.jrssystems.net, and gave you its A record, which said to find it at 66.154.114.98.

Finally on arriving at ns1.jrssystems.net, you had reached the server ultimately authoritative all the way down to the ''third'' level domain - '''www'''.freebsdwiki.net. Since that's as far as you were trying to go, for the first time you were given an actual answer, that the host (aka A record</a>) you were looking for could be found at 66.154.114.98. At that point, your DNS resolver handed that final IP address over to your web browser, which then requested the server at that IP address for this web page, and here you are.

[[Category:FreeBSD Terminology]]

← Older revision		Revision as of 19:22, 21 May 2006
Line 1:		Line 1:
−	The '''root servers''' are the top tier of nameservers which contain the necessary information to resolve each of the [[top level ~~domains~~]] of the internet. There are currently several clusters of root servers. Within each cluster, the member servers are spread out geographically both to minimize [[latency]] and to maximize [[fault tolerance]] for the internet as a whole. The separate clusters service separate top level domains; if you initially query a root server which is not a member of the proper cluster it will give you the IP address of a server in the correct cluster.	+	The '''root servers''' are the top tier of nameservers which contain the necessary information to resolve each of the [[top level domain]]s of the internet. There are currently several clusters of root servers. Within each cluster, the member servers are spread out geographically both to minimize [[latency]] and to maximize [[fault tolerance]] for the internet as a whole. The separate clusters service separate top level domains; if you initially query a root server which is not a member of the proper cluster it will give you the IP address of a server in the correct cluster.

	Once given this address, you repeat your query to that server. If you are still not in the right cluster to provide [[authoritative nameserver\|authoritative]] answers for the top level domain, you will be forwarded again, and repeat your query again. Once you arrive at the authoritative nameserver for your top level domain, you repeat your query to it, and it will point you to the authoritative nameserver for the second level domain. This process can continue once or more for every subdomain level of the URL you wish to resolve.		Once given this address, you repeat your query to that server. If you are still not in the right cluster to provide [[authoritative nameserver\|authoritative]] answers for the top level domain, you will be forwarded again, and repeat your query again. Once you arrive at the authoritative nameserver for your top level domain, you repeat your query to it, and it will point you to the authoritative nameserver for the second level domain. This process can continue once or more for every subdomain level of the URL you wish to resolve.

@@ Line 20: / Line 20: @@
           ;; ADDITIONAL SECTION:          <font color="blue">ns1.jrssystems.net.</font>     172800  <font color="blue">IN      A       66.154.114.98</font>
-Following directions, next we ask <font color="blue">a.gtld-servers.net</font> - but it doesn't know the <font color="red">answer</font> either.  However, it does know that the authoritative nameserver (<font color="blue">NS</font>) for '''freebsdwiki.net''' - the ''second'' level domain of the URL you wanted - is ns1.jrssystems.net.  And just like a.root-servers.net, it gave you the corresponding <font color="blue">A record</font> before you could even ask.  Next step: <font color="blue">66.154.114.98</font>.
+Following directions, next we ask <font color="blue">a.gtld-servers.net</font> the exact same question - but it doesn't know the <font color="red">answer</font> either.  However, it does know that the authoritative nameserver (<font color="blue">NS</font>) for '''freebsdwiki.net''' - the ''second'' level domain of the '''www.freebsdwiki.net''' - is ns1.jrssystems.net.  And just like a.root-servers.net, it gave you the corresponding <font color="blue">A record</font> before you could even ask.  Next step: <font color="blue">66.154.114.98</font>.
   workstation# '''dig @ns1.jrssystems.net <font color="blue">www</font>.<font color="green">freebsdwiki.net</font>'''
@@ Line 26: / Line 26: @@
           <font color="green">''';; ANSWER SECTION:              www.freebsdwiki.net.       300  IN      A       66.154.114.98'''</font>
-Finally, we ask <font color="blue">ns1.jrssystems.net</font> for the last piece of the puzzle - '''www'''.freebsdwiki.net.  Since <font color="blue">ns1.jrssystems.net</font> is authoritative for both the third (www) and second (freebsdwiki) subdomains of the .net top level domain, we are given the final <font color="green">answer</font> to our query, instead of being handed off to another nameserver.  And now that the DNS resolver has the right <font color="green">A record</font> for the URL we wanted, it extracted <font color="green">66.154.114.98</font> from it, handed that to your web browser, which then fetched the web page, and here we are.
+Now we ask <font color="blue">ns1.jrssystems.net</font> for the exact same thing - '''www.freebsdwiki.net'''.  But since <font color="blue">ns1.jrssystems.net</font> is authoritative for both the third (www) and second (freebsdwiki) level subdomains of the .net top level domain, we don't get handed off to anybody else.  This time, we are given the final <font color="green">answer</font> to our query. And now that the DNS resolver has the <font color="green">A record</font> for '''www.freebsdwiki.net''', it extracts <font color="green">66.154.114.98</font> from it, hands that to your web browser, which then fetches the web page, and here you are.
 [[Category:FreeBSD Terminology]]

@@ Line 3: / Line 3: @@
 Once given this address, you repeat your query to that server.  If you are still not in the right cluster to provide [[authoritative nameserver|authoritative]] answers for the top level domain, you will be forwarded again, and repeat your query again.  Once you arrive at the authoritative nameserver for your top level domain, you repeat your query to it, and it will point you to the authoritative nameserver for the second level domain.  This process can continue once or more for every subdomain level of the URL you wish to resolve.
-For example, when you visited www.freebsdwiki.net, either your own nameserver or your ISP's nameserver had to first resolve the [[DNS record types|A record]] to an IP address, beginning from the root servers and working its way downward, repeating the same query to progressively lower-hierarchy servers until it got its final answer.  That process, were you to repeat it on the command line with the DNS tool [[dig]], would have looked much like this:
+For example, when you visited '''www.freebsdwiki.net''', either your own nameserver or your ISP's nameserver had to first resolve the [[DNS record types|A record]] to an IP address, by starting from the root servers and working its way downward.  At each step, it had to ask a progressively lower-hierarchy server the same question: where is '''www.freebsdwiki.net'''? Finally, the buck was passed all the way down to the bottom, and it got its final answer.
   workstation# '''dig @a.root-servers.net www.freebsdwiki.<font color="blue">net</font>'''
@@ Line 9: / Line 11: @@
           ;; AUTHORITY SECTION:   <font color="blue">NS      A.GTLD-SERVERS.net.</font>
           ;; ADDITIONAL SECTION:          <font color="blue">A.GTLD-SERVERS.net.</font>     172800  <font color="blue">IN      A       192.5.6.30</font>
-−
   workstation# '''dig @a.gtld-servers.net www.<font color="blue">freebsdwiki</font>.<font color="green">net</font>'''
           ;; ->>HEADER<<- QUERY: 1, status: NOERROR, <font color="red">'''ANSWER: 0'''</font>, AUTHORITY: 2, ADDITIONAL: 2
@@ Line 15: / Line 20: @@
           ;; ADDITIONAL SECTION:          <font color="blue">ns1.jrssystems.net.</font>     172800  <font color="blue">IN      A       66.154.114.98</font>
   workstation# '''dig @ns1.jrssystems.net <font color="blue">www</font>.<font color="green">freebsdwiki.net</font>'''
           ;; ->>HEADER<<- QUERY: 1, status: NOERROR, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 2
           <font color="green">''';; ANSWER SECTION:              www.freebsdwiki.net.       300  IN      A       66.154.114.98'''</font>
-Basically, it went like this: first your DNS resolver asked '''a.root-servers.net''' (after finding its IP from your own root hint file) where to find '''www.freebsdwiki.net'''.  It didn't know the <font color="red">answer</font>, but it did know you should be asking one of the <font color="blue">gtld-servers</font> about the .net TLD - so it told you that it knew an <font color="blue">NS</font> (nameserver record) for the .net part of your URL.  And since it figured you would just come right back and pester it for directions to that NS record anyway, it volunteered the corresponding <font color="blue">A record</font>, which contained its actual <font color="blue">IP address</font>, without making you specifically ask for it.
+Finally, we ask <font color="blue">ns1.jrssystems.net</font> for the last piece of the puzzle - '''www'''.freebsdwiki.net.  Since <font color="blue">ns1.jrssystems.net</font> is authoritative for both the third (www) and second (freebsdwiki) subdomains of the .net top level domain, we are given the final <font color="green">answer</font> to our query, instead of being handed off to another nameserver.  And now that the DNS resolver has the right <font color="green">A record</font> for the URL we wanted, it extracted <font color="green">66.154.114.98</font> from it, handed that to your web browser, which then fetched the web page, and here we are.
-−
-So then you asked <font color="blue">a.gtld-servers.net</font>, but it didn't know the <font color="red">answer</font> either.  However, it did know the authoritative nameserver for the ''second'' level domain of the URL you wanted - so it told you that the <font color="blue">NS</font> named ns1.jrssystems.net knew all about '''freebsdwiki.net''', and gave you the corresponding <font color="blue">A record</font> so you could go ask <font color="blue">66.154.114.98</font> about the final third level domain to your URL, the '''www''' .
-−
-Finally, on arriving at <font color="blue">ns1.jrssystems.net</font>, you had reached the server ultimately authoritative all the way down to the final level of subdomain in the URL you originally asked for - '''www'''.freebsdwiki.net.  Since that's as far as you were trying to go, for the first time you were given an actual <font color="green">answer</font> to your query instead of getting passed on to another nameserver.  So now that your DNS resolver had the <font color="green">A record</font> for the URL you wanted, it handed the IP address it contained - <font color="green">66.154.114.98</font> - to your web browser, which could then fetch this web page, and here you are.
 [[Category:FreeBSD Terminology]]

@@ Line 23: / Line 23: @@
 So then you asked <font color="blue">a.gtld-servers.net</font>, but it didn't know the <font color="red">answer</font> either.  However, it did know the authoritative nameserver for the ''second'' level domain of the URL you wanted - so it told you that the <font color="blue">NS</font> named ns1.jrssystems.net knew all about '''freebsdwiki.net''', and gave you the corresponding <font color="blue">A record</font> so you could go ask <font color="blue">66.154.114.98</font> about the final third level domain to your URL, the '''www''' .
-Finally, on arriving at <font color="blue">ns1.jrssystems.net</font>, you had reached the server ultimately authoritative all the way down to the final level of subdomain in the URL you originally asked for - '''www'''.freebsdwiki.net.  Since that's as far as you were trying to go, for the first time you were given an actual <font color="green">answer</font> to your query instead of getting passed on to another nameserver.  So now that your DNS resolver knew the host (aka <font color="green">A record</font>) you were looking for could be found at <font color="green">66.154.114.98</font>, it handed the actual IP address to your web browser, which then requested this server for this web page, and here you are.
+Finally, on arriving at <font color="blue">ns1.jrssystems.net</font>, you had reached the server ultimately authoritative all the way down to the final level of subdomain in the URL you originally asked for - '''www'''.freebsdwiki.net.  Since that's as far as you were trying to go, for the first time you were given an actual <font color="green">answer</font> to your query instead of getting passed on to another nameserver.  So now that your DNS resolver had the <font color="green">A record</font> for the URL you wanted, it handed the IP address it contained - <font color="green">66.154.114.98</font> - to your web browser, which could then fetch this web page, and here you are.
 [[Category:FreeBSD Terminology]]

@@ Line 1: / Line 1: @@
 The '''root servers''' are the top tier of nameservers which contain the necessary information to resolve each of the [[top level domains]] of the internet.  There are currently several clusters of root servers.  Within each cluster, the member servers are spread out geographically both to minimize [[latency]] and to maximize [[fault tolerance]] for the internet as a whole.  The separate clusters service separate top level domains; if you initially query a root server which is not a member of the proper cluster it will give you the IP address of a server in the correct cluster.
-Once given this address, you repeat your query to that server.  If you are still not in the right cluster to provide [[authoritative nameserver|authoritative]] answers for the top level domain, you will be forwarded again, and repeat your query again.  Once you arrive at the [[authoritative nameserver]] for your top level domain, you repeat your query to it, and it will point you to the authoritative nameserver for the second level domain.  This process can continue once or more for every subdomain level of the URL you wish to resolve.
+Once given this address, you repeat your query to that server.  If you are still not in the right cluster to provide [[authoritative nameserver|authoritative]] answers for the top level domain, you will be forwarded again, and repeat your query again.  Once you arrive at the authoritative nameserver for your top level domain, you repeat your query to it, and it will point you to the authoritative nameserver for the second level domain.  This process can continue once or more for every subdomain level of the URL you wish to resolve.
 For example, when you visited www.freebsdwiki.net, either your own nameserver or your ISP's nameserver had to first resolve the [[DNS record types|A record]] to an IP address, beginning from the root servers and working its way downward, repeating the same query to progressively lower-hierarchy servers until it got its final answer.  That process, were you to repeat it on the command line with the DNS tool [[dig]], would have looked much like this:

@@ Line 5: / Line 5: @@
 For example, when you visited www.freebsdwiki.net, either your own nameserver or your ISP's nameserver had to first resolve the [[DNS record types|A record]] to an IP address, beginning from the '''root servers''' and working its way downward, repeating the same query to progressively lower-hierarchy servers until it got its final answer.  That process, were you to repeat it on the command line with the DNS tool [[dig]], would have looked much like this:
-  workstation# '''dig @a.root-servers.net <font color="brown">www.freebsdwiki.net</font>'''
+  workstation# '''dig @a.root-servers.net <font color="brown">www.freebsdwiki.<font size="+1">net</font></font>'''
           ;; ->>HEADER<<- QUERY: 1, status: NOERROR, <font color="red">'''ANSWER: 0'''</font>, AUTHORITY: 13, ADDITIONAL: 14
           ;; AUTHORITY SECTION:   <font color="blue">NS      A.GTLD-SERVERS.net.</font>
           ;; ADDITIONAL SECTION:          <font color="blue">A.GTLD-SERVERS.net.</font>     172800  <font color="blue">IN      A       192.5.6.30</font>
-  workstation# '''dig @a.gtld-servers.net <font color="brown">www.freebsdwiki.net</font>'''
+  workstation# '''dig @a.gtld-servers.net <font color="brown">www.<font size="+1">freebsdwiki</font>.net</font>'''
           ;; ->>HEADER<<- QUERY: 1, status: NOERROR, <font color="red">'''ANSWER: 0'''</font>, AUTHORITY: 2, ADDITIONAL: 2
           ;; AUTHORITY SECTION:   <font color="blue">NS      ns1.jrssystems.net.</font>
           ;; ADDITIONAL SECTION:          <font color="blue">ns1.jrssystems.net.</font>     172800  <font color="blue">IN      A       66.154.114.98</font>
-  workstation# '''dig @ns1.jrssystems.net <font color="brown">www.freebsdwiki.net</font>'''
+  workstation# '''dig @ns1.jrssystems.net <font color="brown"><font size="+1">www</font>.freebsdwiki.net</font>'''
           ;; ->>HEADER<<- QUERY: 1, status: NOERROR, <font color="green">'''ANSWER: 1'''</font>, AUTHORITY: 2, ADDITIONAL: 2
           <font color="green">''';; ANSWER SECTION:              www.freebsdwiki.net.        300     IN      A       66.154.114.98'''</font>
-Basically, it went like this: first you asked a.root-servers.net (after finding its IP from your own root hint file) where to find freebsdwiki.net.  It didn't know the <font color="red">answer</font>, but it did know you should be asking one of the <font color="blue">gtld-servers</font> about the .net TLD - so it told you that it knew an <font color="blue">NS</font> (nameserver record) for the gtld-servers.  And since it figured you would just come right back and pester it for directions to that NS record, it went ahead and gave you the corresponding <font color="blue">IN A</font> (internet-class A record), which contained its actual <font color="blue">IP address</font>, before you specifically asked for it.
+Basically, it went like this: first your DNS resolver asked '''a.root-servers.net''' (after finding its IP from your own root hint file) where to find '''www.freebsdwiki.net'''.  It didn't know the <font color="red">answer</font>, but it did know you should be asking one of the <font color="blue">gtld-servers</font> about the .net TLD - so it told you that it knew an <font color="blue">NS</font> (nameserver record) for the .net part of your URL.  And since it figured you would just come right back and pester it for directions to that NS record anyway, it volunteered the corresponding <font color="blue">A record</font>, which contained its actual <font color="blue">IP address</font>, without making you specifically ask for it.
-So then you asked <font color="blue">a.gtld-servers.net</font>, but it didn't know the <font color="red">answer</font> either.  However, it did know the authoritative nameserver for the ''second'' level domain freebsdwiki.net - so it told you to go ask the <font color="blue">NS</font> ns1.jrssystems.net, and gave you its <font color="blue">A record</font>, which said to find it at <font color="blue">66.154.114.98</font>.
+So then you asked <font color="blue">a.gtld-servers.net</font>, but it didn't know the <font color="red">answer</font> either.  However, it did know the authoritative nameserver for the ''second'' level domain of the URL you wanted - so it told you that the <font color="blue">NS</font> named ns1.jrssystems.net knew all about '''freebsdwiki.net''', and gave you the corresponding <font color="blue">A record</font> so you could go ask <font color="blue">66.154.114.98</font> about the final third level domain to your URL, the '''www''' .
-Finally on arriving at <font color="blue">ns1.jrssystems.net</font>, you had reached the server ultimately authoritative all the way down to the ''third'' level domain - '''www'''.freebsdwiki.net.  Since that's as far as you were trying to go, for the first time you were given an actual <font color="green">answer</font>, that the host (aka <font color="green">A record</a>) you were looking for could be found at <font color="green">66.154.114.98</font>.  At that point, your DNS resolver handed that final IP address over to your web browser, which then requested the server at that IP address for this web page, and here you are.
+Finally, on arriving at <font color="blue">ns1.jrssystems.net</font>, you had reached the server ultimately authoritative all the way down to the final level of subdomain in the URL you originally asked for - '''www'''.freebsdwiki.net.  Since that's as far as you were trying to go, for the first time you were given an actual <font color="green">answer</font> to your query instead of getting passed on to another nameserver.  So now that your DNS resolver knew the host (aka <font color="green">A record</a>) you were looking for could be found at <font color="green">66.154.114.98</font>, it handed the actual IP address to your web browser, which then requested this server for this web page, and here you are.
 [[Category:FreeBSD Terminology]]