Package io.vertx.core.dns

== DNS client Often you will find yourself in situations where you need to obtain DNS informations in an asynchronous fashion.

See: Description

Interface Summary

Interface	Description
DnsClient	Provides a way to asynchronously lookup information from DNS servers.
MxRecord	Represent a Mail-Exchange-Record (MX) which was resolved for a domain.
SrvRecord	Represent a Service-Record (SRV) which was resolved for a domain.

Class Summary

Class	Description
AddressResolverOptions	Configuration options for Vert.x hostname resolver.

Enum Summary

Enum	Description
DnsResponseCode	Represents the possible response codes a server may send after receiving a query.

Exception Summary

Exception	Description
DnsException	Exception which is used to notify the AsyncResult if the DNS query returns a DnsResponseCode which indicates and error.

Package io.vertx.core.dns Description

== DNS client Often you will find yourself in situations where you need to obtain DNS informations in an asynchronous fashion. Unfortunally this is not possible with the API that is shipped with the Java Virtual Machine itself. Because of this Vert.x offers it's own API for DNS resolution which is fully asynchronous. To obtain a DnsClient instance you will create a new via the Vertx instance. [source,$lang] ---- examples.DNSExamples#example1 ---- Be aware that you can pass in a varargs of InetSocketAddress arguments to specifiy more then one DNS Server to try to query for DNS resolution. The DNS Servers will be queried in the same order as specified here. Where the next will be used once the first produce an error while be used. === lookup Try to lookup the A (ipv4) or AAAA (ipv6) record for a given name. The first which is returned will be used, so it behaves the same way as you may be used from when using "nslookup" on your operation system. To lookup the A / AAAA record for "vertx.io" you would typically use it like: [source,$lang] ---- examples.DNSExamples#example2 ---- === lookup4 Try to lookup the A (ipv4) record for a given name. The first which is returned will be used, so it behaves the same way as you may be used from when using "nslookup" on your operation system. To lookup the A record for "vertx.io" you would typically use it like: [source,$lang] ---- examples.DNSExamples#example3 ---- === lookup6 Try to lookup the AAAA (ipv6) record for a given name. The first which is returned will be used, so it behaves the same way as you may be used from when using "nslookup" on your operation system. To lookup the A record for "vertx.io" you would typically use it like: [source,$lang] ---- examples.DNSExamples#example4 ---- === resolveA Try to resolve all A (ipv4) records for a given name. This is quite similar to using "dig" on unix like operation systems. To lookup all the A records for "vertx.io" you would typically do: [source,$lang] ---- examples.DNSExamples#example5 ---- === resolveAAAA Try to resolve all AAAA (ipv6) records for a given name. This is quite similar to using "dig" on unix like operation systems. To lookup all the AAAAA records for "vertx.io" you would typically do: [source,$lang] ---- examples.DNSExamples#example6 ---- === resolveCNAME Try to resolve all CNAME records for a given name. This is quite similar to using "dig" on unix like operation systems. To lookup all the CNAME records for "vertx.io" you would typically do: [source,$lang] ---- examples.DNSExamples#example7 ---- === resolveMX Try to resolve all MX records for a given name. The MX records are used to define which Mail-Server accepts emails for a given domain. To lookup all the MX records for "vertx.io" you would typically do: [source,$lang] ---- examples.DNSExamples#example8 ---- Be aware that the List will contain the MxRecord sorted by the priority of them, which means MX records with smaller priority coming first in the List. The MxRecord allows you to access the priority and the name of the MX record by offer methods for it like: [source,$lang] ---- examples.DNSExamples#example9 ---- === resolveTXT Try to resolve all TXT records for a given name. TXT records are often used to define extra informations for a domain. To resolve all the TXT records for "vertx.io" you could use something along these lines: [source,$lang] ---- examples.DNSExamples#example10 ---- === resolveNS Try to resolve all NS records for a given name. The NS records specify which DNS Server hosts the DNS informations for a given domain. To resolve all the NS records for "vertx.io" you could use something along these lines: [source,$lang] ---- examples.DNSExamples#example11 ---- === resolveSRV Try to resolve all SRV records for a given name. The SRV records are used to define extra informations like port and hostname of services. Some protocols need this extra informations. To lookup all the SRV records for "vertx.io" you would typically do: [source,$lang] ---- examples.DNSExamples#example12 ---- Be aware that the List will contain the SrvRecords sorted by the priority of them, which means SrvRecords with smaller priority coming first in the List. The SrvRecord allows you to access all informations contained in the SRV record itself: [source,$lang] ---- examples.DNSExamples#example13 ---- Please refer to the API docs for the exact details. === resolvePTR Try to resolve the PTR record for a given name. The PTR record maps an ipaddress to a name. To resolve the PTR record for the ipaddress 10.0.0.1 you would use the PTR notion of "1.0.0.10.in-addr.arpa" [source,$lang] ---- examples.DNSExamples#example14 ---- === reverseLookup Try to do a reverse lookup for an ipaddress. This is basically the same as resolve a PTR record, but allows you to just pass in the ipaddress and not a valid PTR query string. To do a reverse lookup for the ipaddress 10.0.0.1 do something similar like this: [source,$lang] ---- examples.DNSExamples#example15 ---- include::override/dns.adoc[]