Selecting a faster DNS server is extremely important in Xeams. Several rules, such as RBL LookupsBlack-listed domain lookup, MX, A, SPF lookup and others
run queries against a DNS server. Faster the lookups, faster Xeams will be able to process incoming messages.
By design, DNS servers create a lookup chain. For example, if a DNS server cannot resolve a query locally, it will
try getting that answer from the next server up. The more servers get involved in a lookup, the slower a result is fetched
and Xeams will spend a long time processing an email.
When it comes to DNS servers, bigger is better. Every DNS server will cache results. Therefore, it is always better to use
a DSN server that will have a large cache.
Often administrators use a local DNS server, running on their LAN. Relatively speaking, this local DNS server's cache will
be significantly less than the DNS server for your ISP.
Therefore, we strongly recommend using a DNS server belonging to your ISP instead of your router or another DNS server on your LAN.
DO NOT use a public DNS server, such as Googles (220.127.116.11). For some reason, Google's DNS server does not work nicely with RBL servers. Check this link on SpamHaus for details.
Where to specify a DNS server
Although there is a way to specify a DNS server in Xeams, we recommend you change the DNS server at the machine level
where Xeams is running. That is because your machine also contains a cache and will make subsequent lookups faster.
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