A Domain Name Server (DNS Server) is the role of converting the “www” format domain address to a numeric IP address of the target which the domain points to. For example, you input www.gogototo.com in your web browser, your internet routine will try to find out the name server of gogototo.com, and then the name server will give the target server which gogototo.com website is hosted on, so that you can view gogototo.com website. A real of domain routine is much more complicate than we descripted here, but it is not our major topic today.
Why We Need to Change Domain Name Server ?
When we register a new domain, we have a default name server set already by domain registrar normally. If any reason such as you building a new website using this domain but your website hosting is from another service, you normally have to change the domain name servers which are from your hosting service company.
However, what we should know is that a domain name server switching needs a waiting time. You can not see the new name server works right after you changed on the domain. Normally you have to wait the new name server taking effect (sometimes it is called DNS propagation) for from several hours to couples of day.
Why Does New Domain Name Server Not Work ?
First we have to understand why we have to wait for name server switching. The name sever switching involves multiple servers and objects, all of them need to update their data or system for the new domain name servers, and, different servers and objects have their own system updating interval settings, the interval might be from several hours to couple of days. That is why sometimes you had to wait up to 48 hours or more.
If you think the new DNS server switching is too slow, you can try to check the following factors to find real reason:
1: Domain TTL: The time period for a server caches domain DNS information.
TTL is set on domain configuration. If you set TTL to one hour, related server will “hold” domain information in one hour, and then ask information from domain’s authoritative name server again;
2: Domain TLD registry:
Domain registry is the domain management organization. There are different domain registries in the world. For example .com and .ca, they are belongs to different domain registers.
The domain registry publishes domain name server information to a specific place such as root zone so that all other servers can get the publishing information. Different domain registry publish domain information from several minutes to 24 hours or more.
3: Your ISP Caching
ISP is your Internet Service Provider. For example, in Canada, the ISP could be Rogers, Bell or others. Normally ISP use recursive and set their own cache to store past address lookups. The major reason why ISPs use cache just because of speed up address lookup.
Normally an ISP cache the lookup information from 1 to 24 hours, there are also some ISP caches longer time, such as 48 hours or longer, which is some strange to customers.
4: Your computer’s DNS caching
Sometimes the slow DNS information effect caused by your own computer’s DNS caching. Please run the following commands on your computer to reset.
– Windows: inconfig /flushdns
– Mac: dscacheutil –flushcache or lookupd -flushcache
– Linux: /etc/init.d/nscd restart
A Real Caching Issue We Have Had
We met an new name (DNS) server switching delay issue: After we setting new name servers on a domain in one night, we got the DNS information switching successfully at the second day and we could visit the new website from our office which was using Rogers internet service, but we could not visit the new website from home using the same laptop, what we could see was still old web pages.
Since we were using the same computer, the problem obviously was from our home ISP service. We were using another ISP for home internet. So we had to contact to our ISP to resolve the issue. We guessed their caching was too long, or there might be issue on their caching.
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