How to check DNS propagation on Linux
Posted on: 04/01/2014 09:57 AM

Xmodulo shows you how to check DNS propagation on Linux

How to check DNS propagation on Linux

While DNS introduces human-readable naming schemes for Internet hosts, it also brings with it extra overhead associated with resolving names to IP addresses. For end users, this overhead means additional DNS lookup latency for accessing any Internet host. For service providers, this implies the performance-critical DNS infrastructure that needs to be maintained. Minimizing these overheads has led to the extensive use of "caching" throughout DNS hierarchy. For example, there are web browser/OS's built-in DNS cache; DNS caching server of the local network; and the cache of local DNS servers operated by service providers, etc.

Such a deep chain of DNS caches has implication when it comes to "updating" DNS records. Oftentimes, when you update the DNS record of your host, the update is not immediately visible to the world. Instead, an old DNS record can temporarily be served from various DNS caches. Local DNS servers typically keep each DNS entry in their cache for up to a certain length of time, known as "time-to-live" (TTL), which can range from minutes to a day. Thus a typical DNS propagation delay (i.e., time taken to see any DNS update to propagate globally) is 24-48 hours.

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