When you modify DNS records contained in your domain name's zone file, the propagation of your changes across the internet and to servers worldwide (the time it takes for the information to propagate and be effectively applied to all DNS servers) can take up to 48 or 72 hours.
We strive to implement these changes as quickly as possible, including lowering TTLs to a minimum, but nevertheless this propagation time also depends on many factors that we do not control.
Regarding email and the DNS system, the modification of the MX (Mail eXchange) record of the DNS zone of your domain, i.e. the modification of the email hosting server associated with your domain, takes effect gradually, given the operation of the DNS system itself in which the propagation of the new parameters depends on the responsiveness of the other servers that copy the information (cache update), and not solely on our own services.
During the switch from one server to another, messages may start arriving on the new server, while others will continue to arrive on the old mail server, and this for several hours/days after the MX change (more info here to ensure email continuity during a mail server change).
Factors that can affect DNS propagation time include:
- Your TTL (Time To Live) settings – A TTL value, which you can modify, is configured for each DNS record in your domain name's zone file. The TTL value, expressed in seconds, represents the period during which servers cache data related to your DNS records. For example, if you specify a TTL value of one hour (3600 seconds) for a record, the servers will store the record's information locally for that hour before retrieving updated data from your master NS server. Short TTL values (300 seconds) can therefore significantly improve the propagation speed of your changes. However, short TTL values can also increase the number of queries sent to your master NS server, and this increased load can slow down the processing capacity and responsiveness of your NS server and the DNS system. It is therefore recommended to lower the TTL to a minimum (300s) before making any changes (ideally 1 day), and then raise them again after the changes have been made.
- Your ISP (Internet Service Provider) : Your ISP caches the DNS records corresponding to your domain name; it stores the data locally on its servers for a period of time rather than constantly retrieving new data from your DNS server. This can speed up response times, improve internet browsing, and reduce traffic, which slows down the propagation time of your DNS changes. Furthermore, some ISPs ignore TTL settings and only refresh their cached DNS records every two or three days.
- The registry managing your domain name extension (.com, .fr, .org, .net, etc.) – If you modify the NS servers associated with your domain name in your customer area, we forward your modification request to the relevant registry within minutes. The registry then publishes your reference NS records in its root zone. Most registries update their root zones very quickly, also within minutes; this is notably the case, for example, with VeriSign (which manages .com, among others), which updates its .COM domain name zones every three minutes. However, not all registries are updated so quickly. Indeed, some registries protect their root name servers (NS) against excessive use. To do this, they specify a high TTL value, which can reach or even sometimes exceed 48 hours for NS records. Finally, although it is not necessary for recursive name servers to cache root NS records, some ISPs do this anyway, which results in a longer propagation time ( https://whois.icann.org/fr/processus-denregistrement-des-noms-de-domaine ).