Unit DNS

`DNS_TIMEOUT = 5000;`	We wait for 5 seconds for a DNS reply
`DNS_RETRIES = 4;`	Try the request 4 times

`DNS_HEADER_SIZE = 12;`	SizeOf(TDNSHeader);

`DNS_QUESTION_SIZE = 4;`	SizeOf(TDNSQuestion);
`DNS_RESOURCE_SIZE = 10;`	SizeOf(TDNSResource); Not including Record Data

`MAX_DNS_NAME = 255;`
`MAX_DNS_LABEL = 63;`
`MAX_DNS_MESSAGE = 512;`	Maximum Size of DNS Message

`DNS_FLAG_RESPONSE = $8000;`	query = 0, response = 1
`DNS_FLAG_AUTHORITY = $0400;`	Authoritative answer
`DNS_FLAG_TRUNCATED = $0200;`	Truncation, response was cut off at 512
`DNS_FLAG_DO_RECURSE = $0100;`	Recursion desired
`DNS_FLAG_CAN_RECURSE = $0080;`	Recursion available

`DNS_OPCODE_MASK = $7800;`	Opcode
`DNS_RESPONSE_MASK = $000F;`	Response code

`DNS_QUERY = 0;`	A standard query
`DNS_INV_QUERY = 1;`	An inverse query
`DNS_COMP_QUERY_MULTI = 2;`	A completion query, multiple reply (Obsolete)
`DNS_COMP_QUERY_SINGLE = 3;`	A completion query, single reply (Obsolete)

Contents

`DNS_TYPE_A = 1;`	Host address resource record (RR)
`DNS_TYPE_NS = 2;`
`DNS_TYPE_MD = 3;`
`DNS_TYPE_MF = 4;`
`DNS_TYPE_CNAME = 5;`
`DNS_TYPE_SOA = 6;`
`DNS_TYPE_MB = 7;`
`DNS_TYPE_MG = 8;`
`DNS_TYPE_MR = 9;`
`DNS_TYPE_RT_NULL = 10;`
`DNS_TYPE_WKS = 11;`
`DNS_TYPE_PTR = 12;`	A domain name ptr
`DNS_TYPE_HINFO = 13;`
`DNS_TYPE_MINFO = 14;`
`DNS_TYPE_MX = 15;`	Mail exchange

`DNS_CLASS_IN = 1;`	ARPA internet class
`DNS_CLASS_CS = 2;`
`DNS_CLASS_WILD = 255;`	Wildcard for several of the classifications