If the refresh value is say 3 hours, your secondary server is polling your primary server every 3 hours and updating the cache. Lets assume you have a zone files, each with 3 hours refresh rate.
You can imagine the bandwidth that must be getting used. This is especially true if the servers are on 2 separate physical servers.
An increase in the Refresh rate can effectively reduce bandwidth usage between the primary and secondary server. The time it takes to access a website on a browser includes the time it takes to look it up on the domain name server. In effect, reducing the lookups to the nameserver. However, this also means that if you make changes to the DNS record, it will take longer to propagate.
If you require to make frequent updates to your DNS records, make sure your Minimum value is lesser than 1 day.
That means longer lookup times, but accurate information for the clients. If you are planning a major update on the DNS zone file say moving to another server or hosting service , reduce the Minimum value a couple of days prior to the change. Then make the change and then jack up the minimum value again.
This way the caching clients all over the world will pick up the changes quicker and yet you do not need to sacrifice on site speed thereafter. Always keep a secondary DNS server and keep a higher Expiry value. This will mean that even if the Primary server goes down, the secondary will have the cached copy for as long as the Expiry value stands and it will keep serving lookups.
Keeping a secondary server but a low expiry value defeats the purpose of a Backup. You have set the new SOA values, and you want to know whether the update has taken place. For example to check out the SOA records of yahoo.
About the author: Sangeetha Naik heads Bobcares. She is the co-founder of Poornam Info Vision Ltd. Sangeetha is a Computer Engineer based in India and has over 7 years of experience in the Hosting industry. Her articles have been published both online as well as in print. She can be contacted via Contact us form. My SOA record looks like this. Please make sure : 1.
This article is truly useful in helping me understand the concept of DNS. Well, actually the problem is not really visible as I still can see my site. I then contacted their Support and they can resolve the problem. Everything looks good now and I will certainly get back often to read more articles from you. Two thumbs up! One thing in your example you show Expiry — but recommend 2 weeks! Yes, the ideal value should be around 2 weeks.
This is actually the time in seconds you would expect your slave to serve requests not bothering if it is stale data that it is serving. In this format, one can thus identify the date the version was created. With each change that is made on the same day, the version number increases by one. On a new day, the serial number adjusts to the appropriate place and the version number is reset to The SOA record ends with three to four time specifications — each in seconds.
It is important for this specification to be smaller than the previous one. Should the server continue to send old zone file data to the clients submitting requests, it may no longer be valid.
This may lead to connection issues and security risks. This corresponds to the time to live, as you may be familiar with from other DNS record types. It specifies how long a client may hold the requested information in the cache before a new request must be sent. The fields can simply be listed one after the one on a line. While this is not very complex with other entry types, the SOA record is rather comprehensive in comparison.
In order to create more clarity, the fields are usually arranged in nests and underneath each other. This notation is used to determine the TTL and domain name upfront. The symbol at the beginning of the record refers to the origin directive. In order to nest the time specifications and to divide them among several lines, parentheses are introduced.
No zone file is valid without an SOA entry at the beginning. In practice, SOA records look like this:. In this zone file snippet, you can see how — in order to make the placement clearer — we have entered more information than just the SOA record. The file begins with the domain name specification in this case, example. This is then followed by the SOA record. The period is enabled through the backslash — in this case a masking character. The next period then replaces the symbol for the actual address; the following one, as usual, defines the top-level domain TLD.
Using a bracket, you can open the nested area which can then be divided among several lines. However, it is also possible to write all values behind one another and to only separate them with empty spaces.
In this example, we have written the definitions for the specific values behind them. These are only comments that can be selected themselves or simply omitted.
In the case of DNS records, a semicolon can be used to mark those comments that are solely intended for human users. Subsequently, we have also included a NS record and an A record in the zone file example. You can see that the SOA record must be placed before all the other records — but not before the domain and TTL directives. On the following page, you already receive a result, though only for the A record. You can therefore select SOA in the appropriate field and run another search at the touch of a button.
What does that mean? The SOA Record specifies authoritative information about a DNS zone, including the primary name server, the email of the domain administrator, the domain serial number, and several timers relating to refreshing the zone.
The example shows a dig result for khtechs. For this example, the actual SOA Record is:. User Tools Log In. Site Tools Search. Sidebar Navigation Home. My KnownHost.
Software Addons.
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