Shulou(Shulou.com)05/31 Report--

What is the TTL value of the domain name? For this problem, this article introduces the corresponding analysis and solution in detail, hoping to help more small partners who want to solve this problem find a simpler and easier way.

With the development of science and technology, some nouns really need to be carefully done to better understand what they mean. Do you know what the TTL value of the domain name means? We often appear TTL when resolving domain names, which defaults to 10 minutes.

What is the TTL value of a domain name?

TTL(Time-To-Live) is the length of time a domain name resolution record lives in a DNS server. When a DNS server receives a resolution request, it will send a resolution request to the NS server specified by the domain name to obtain a resolution record; after obtaining this record, the record will be stored in the DNS server for a period of time. During this period of time, if it receives a resolution request for this domain name again, the DNS server will no longer send a request to the NS server, but directly return the record just obtained; and the time this record is retained on the DNS server is the TTL value.

Application of TTL value setting:

1. Increase TTL value to save domain name resolution time and speed up website visits.

In general, the various records of domain names are rarely changed, and it is likely that there will be no changes in months or years. We can increase the TTL value of the domain name record so that the record will be cached in the DNS server for a longer period of time, so that when we visit this website for a longer period of time, the DNS server of the local ISP does not need to issue a resolution request to the NS server of the domain name, and returns the domain name resolution record directly from the cache.

TTL values for many domestic and international platforms are in seconds, and many default values are 3600, which is the default cache for 1 hour. This value is a bit small. Will someone change the domain name record once an hour? You can expand this value appropriately according to your own needs, for example, to cache a day set to 86400. Godaddy's TTL settings are intuitive, but there are only 5 values to choose from, and the same is true for instant switching to advanced settings mode, which is a bit rigid. LifeTyper.com TTL value is set to *** value 1 week due to the profit environment of the site, setting it to a higher value may cause unnecessary trouble, such as when you change space, these old records will take a long time to expire and be updated.

2. Reduce TTL value to reduce inaccessible time when changing spaces.

99.9% of the replacement space will have DNS record changes, because of caching problems, the new domain name record may take effect in some places, but in some places it may take a day or two or even longer to take effect. As a result, some people may have access to the new server, while others may have access to the old server. It's not a big deal if it's just access, but it's a bit of a hassle if it involves sending mail, and maybe some important mail gets sent to the old server that's down.

In order to minimize the time difference between these locations, it is reasonable to:

1)Let's look at the current TTL value of the domain name, which we assume is 1 day.

2)Change TTL to the minimum settable value, and if possible, recommend 1 minute, which is 60.

3)Wait a day to ensure that DNS server caches everywhere expire and update records.

4)Set to modify the new record, this time around the DNS can be updated to the new record at the fastest speed.

5)After confirming that DNS updates are complete, set TTL to the value you want, TTL=60 is still too low.

Keep in mind that all this can work on the premise that those DNS servers fully comply with these standards and specifications, otherwise how to set TTL on NS servers is useless, but so far no DNS server has been found so unruly.

The problem is that there is no real high-speed NS and DNS server. As mentioned here, Dodaddy got *** points in foreign evaluations, but when used in China, the speed is not much faster than Wanwang; Wanwang has outstanding performance in domestic speed, but the score in foreign evaluation websites may be very low. If you have the money to deploy a large number of CDN acceleration servers and NS servers all over the world like Google and Microsoft, of course there is no problem. The problem is that this is impossible for most websites. It is not impossible to have both domestic and foreign, but it is very difficult.

One might think that you can speed up resolution by specifying two NS records for a domain name (one domestic and one foreign), but this is impossible because resolution requests are sent to the second NS server only if the DNS server fails to retrieve a record from the first NS server. One of the cheapest and most effective ways I know of to speed things up is to modify the TTL value of the domain name record mentioned above.

3. The PING command returns results, modifying its TTL value to protect security:

Under normal circumstances, we ping the TTL value returned to you by the other party, roughly determine whether the system type of the target host is Windows series or UNIX/Linux series. Usually, the TTL value returned by the Windows series system is between 100 and 130, while the TTL value returned by the UNIX/Linux series system is between 240 and 255. For example, the TTL returned by Ping www.ieeye.com is 240. The other party's system is likely to be Linux, and the TTL of another target is 120. The system it uses may be Windows.

About the TTL value of the domain name is what the answer to the question is shared here, I hope the above content can be of some help to everyone, if you still have a lot of doubts not solved, you can pay attention to the industry information channel to learn more related knowledge.

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