Unit DNS
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Description
Note: DNS Client is IPv4 based, for IPv6 see new Winsock2 functions
See RFC 1035 Section 4 for details
Constants
DNS specific constants 
 DNS_*  DNS_TIMEOUT = 5000;
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We wait for 5 seconds for a DNS reply | 
 DNS_RETRIES = 4;
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Try the request 4 times | 
 DNS_HEADER_SIZE = 12;
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SizeOf(TDNSHeader); | 
 DNS_QUESTION_SIZE = 4;
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SizeOf(TDNSQuestion); | 
 DNS_RESOURCE_SIZE = 10;
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SizeOf(TDNSResource); Not including Record Data | 
 MAX_DNS_NAME = 255;
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 MAX_DNS_LABEL = 63;
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 MAX_DNS_MESSAGE = 512;
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Maximum Size of DNS Message | 
 
DNS flag constants 
 DNS_FLAG_*  DNS_FLAG_RESPONSE = $8000;
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query = 0, response = 1 | 
 DNS_FLAG_AUTHORITY = $0400;
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Authoritative answer | 
 DNS_FLAG_TRUNCATED = $0200;
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Truncation, response was cut off at 512 | 
 DNS_FLAG_DO_RECURSE = $0100;
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Recursion desired | 
 DNS_FLAG_CAN_RECURSE = $0080;
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Recursion available | 
 
DNS field masks constants 
 DNS_OPCODE_*  DNS_OPCODE_MASK = $7800;
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Opcode | 
 DNS_RESPONSE_MASK = $000F;
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Response code | 
 
DNS query code constants 
 DNS_QUERY*  DNS_QUERY = 0;
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A standard query | 
 DNS_INV_QUERY = 1;
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An inverse query | 
 DNS_COMP_QUERY_MULTI = 2;
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A completion query, multiple reply (Obsolete) | 
 DNS_COMP_QUERY_SINGLE = 3;
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A completion query, single reply (Obsolete) | 
 
DNS response code constants 
 DNS_NO_*  DNS_NO_ERROR = 0;
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 DNS_FORMAT_ERROR = 1;
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 DNS_SERVER_FAILURE = 2;
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 DNS_NAME_ERROR = 3;
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 DNS_NOT_IMPLEMENTED = 4;
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 DNS_REFUSED = 5;
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DNS record type constants 
 DNS_TYPE_*  DNS_TYPE_A = 1;
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Host address resource record (RR) | 
 DNS_TYPE_NS = 2;
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 DNS_TYPE_MD = 3;
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 DNS_TYPE_MF = 4;
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 DNS_TYPE_CNAME = 5;
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 DNS_TYPE_SOA = 6;
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 DNS_TYPE_MB = 7;
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 DNS_TYPE_MG = 8;
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 DNS_TYPE_MR = 9;
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 DNS_TYPE_RT_NULL = 10;
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 DNS_TYPE_WKS = 11;
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 DNS_TYPE_PTR = 12;
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A domain name ptr | 
 DNS_TYPE_HINFO = 13;
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 DNS_TYPE_MINFO = 14;
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 DNS_TYPE_MX = 15;
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Mail exchange | 
DNS address class constants 
 DNS_CLASS_*  DNS_CLASS_IN = 1;
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ARPA internet class | 
 DNS_CLASS_CS = 2;
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 DNS_CLASS_WILD = 255;
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Wildcard for several of the classifications | 
 
DNS message compression constants 
 DNS_POINTER_*  DNS_POINTER_MASK = $C0;
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Mask to indicate pointer to previously used name | 
Type definitions
To be documented
Public variables
To be documented
Function declarations
Initialization functions
procedure DNSInit;
Description: To be documented
| Note | None documented | 
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function DNSStart:LongWord;
Description: To be documented
| Note | None documented | 
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function DNSStop:LongWord;
Description: To be documented
| Note | None documented | 
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