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Difference between revisions of "DNS"
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== DNS Servers Open to Public Query == | == DNS Servers Open to Public Query == | ||
{| | This is '''not''' an exhaustive list of publicly accessible DNS servers. There are more, those listed below are a subset, and may be better or worse than others. | ||
|- | |||
{|class="vwikitable" | |||
|- | |||
! IP Address !! Provider !! Location | ! IP Address !! Provider !! Location | ||
|- | |- | ||
| 8.8.8.8 || Google | | 8.8.8.8 || [https://developers.google.com/speed/public-dns/ Google] || Global (routed via [http://en.wikipedia.org/wiki/Anycast Anycast]) | ||
|- | |- | ||
| 8.8.4.4 || Google | | 8.8.4.4 || [https://developers.google.com/speed/public-dns/ Google] || Global (routed via [http://en.wikipedia.org/wiki/Anycast Anycast]) | ||
|- | |||
| 156.154.70.1 || [http://www.dnsadvantage.com/index.html DNSadvantage] || [http://www.dnsadvantage.com/dnsadv/node_locations.html Global] | |||
|- | |- | ||
| 156.154. | | 156.154.71.1 || [http://www.dnsadvantage.com/index.html DNSadvantage] || [http://www.dnsadvantage.com/dnsadv/node_locations.html Global] | ||
|- | |- | ||
| | | 208.67.220.220 || [http://www.opendns.com/ OpenDNS] || [http://www.opendns.com/technology/network-map Global, mainly US] (routed via [http://en.wikipedia.org/wiki/Anycast Anycast]) | ||
|- | |- | ||
| 208.67.220. | | 208.67.220.222 || [http://www.opendns.com/ OpenDNS] || [http://www.opendns.com/technology/network-map Global, mainly US] (routed via [http://en.wikipedia.org/wiki/Anycast Anycast]) | ||
|- | |- | ||
| | | 4.2.2.1 || Level 3 || Probably global (routed via [http://en.wikipedia.org/wiki/Anycast Anycast]) | ||
|- | |- | ||
| 4.2.2. | | 4.2.2.2 <ref name="4.2.2.2" /> || Level 3 || Probably global (routed via [http://en.wikipedia.org/wiki/Anycast Anycast]) | ||
|- | |- | ||
| 194.72.9.34 || [http://www.bt.com/ BT] || UK | | 194.72.9.34 || [http://www.bt.com/ BT] || UK | ||
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http://theos.in/windows-xp/free-fast-public-dns-server-list/ | http://theos.in/windows-xp/free-fast-public-dns-server-list/ | ||
== NSLookup == | == Troubleshooting == | ||
=== NSLookup === | |||
NSLookup is a Name Server Lookup/Query tool which exists in both Unix and Windows distributions, and generally speaking, functionaly the same regardless of which version you're using. To start, run <code>nslookup</code> from the command line. | NSLookup is a Name Server Lookup/Query tool which exists in both Unix and Windows distributions, and generally speaking, functionaly the same regardless of which version you're using. To start, run <code>nslookup</code> from the command line. | ||
{| | {|class="vwikitable" | ||
|- | |- | ||
! Command !! Description | ! Command !! Description | ||
|- | |- | ||
| Line 59: | Line 62: | ||
microsoft.com MX preference = 10, mail exchanger = mail.messaging.microsoft.com | microsoft.com MX preference = 10, mail exchanger = mail.messaging.microsoft.com | ||
> | > | ||
=== Propagation === | |||
One of the features of DNS is the way that records get cached around the globe. Meaning that any changes to existing records have to ripple around. Generally changes take up to 72 hrs (3 days) to take effect. | |||
However, you can change the [[Acronyms#T|TTL]] of record to ensure that it needs to be refreshed from its authoritative name-server more frequently than normal, ensuring that any changes apply more quickly. | |||
'''To view the propagation of a record around the world see http://www.whatsmydns.net''' | |||
=== General === | |||
The following site has a number of tools that allow you to investigate how a domain is viewed externally/publicly... | |||
http://enc.com.au/itools/ | |||
== Notes == | |||
<references> | |||
<ref name="4.2.2.2">For further info on 4.2.2.2 see http://www.tummy.com/Community/Articles/famous-dns-server/</ref> | |||
</references> | |||
[[Category:Networking]] | |||