<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> <HTML ><HEAD ><TITLE >servername Lookup</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK REL="HOME" TITLE="FreeTDS User Guide" HREF="index.htm"><LINK REL="UP" TITLE="Install FreeTDS" HREF="install.htm"><LINK REL="PREVIOUS" TITLE="Choosing a TDS protocol version" HREF="choosingtdsprotocol.htm"><LINK REL="NEXT" TITLE="The freetds.conf file" HREF="freetdsconf.htm"><LINK REL="STYLESHEET" TYPE="text/css" HREF="userguide.css"><META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=utf-8"></HEAD ><BODY CLASS="SECT1" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#840084" ALINK="#0000FF" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" ><SPAN CLASS="PRODUCTNAME" >FreeTDS</SPAN > User Guide: A Guide to Installing, Configuring, and Running <SPAN CLASS="PRODUCTNAME" >FreeTDS</SPAN ></TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="choosingtdsprotocol.htm" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" >Chapter 3. Install <SPAN CLASS="PRODUCTNAME" >FreeTDS</SPAN ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="freetdsconf.htm" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECT1" ><H1 CLASS="SECT1" ><A NAME="NAME.LOOKUP" ><TT CLASS="REPLACEABLE" ><I >servername</I ></TT > Lookup</A ></H1 ><P ><SPAN CLASS="PRODUCTNAME" >FreeTDS</SPAN > converts the servername to an IP address by following the steps below, stopping when it succeeds. <P ></P ><P ><B >Name lookup sequence <A NAME="AEN914" HREF="#FTN.AEN914" ><SPAN CLASS="footnote" >[1]</SPAN ></A > </B ></P ><OL TYPE="1" ><LI ><P >Find <TT CLASS="REPLACEABLE" ><I >servername</I ></TT > in <TT CLASS="FILENAME" >freetds.conf</TT >. If a section with that name exists, use the hostname, port, and TDS version specified therein.</P ></LI ><LI ><P >Attempt to convert <TT CLASS="REPLACEABLE" ><I >servername</I ></TT > to an IP address with <CODE CLASS="FUNCTION" >inet_addr(3)</CODE >.</P ></LI ><LI ><P >Request name-lookup from the operating system via <CODE CLASS="FUNCTION" >gethostbyname(3)</CODE > or similar.</P ></LI ></OL > If the TDS version and port are not read from <TT CLASS="FILENAME" >freetds.conf</TT >, they are derived from the compiled-in defaults and overridden by applicable environment variables.</P ><P >As you can see, if most of your servers use the same TDS version and answer to the default port, then you don't need to list them all in <TT CLASS="FILENAME" >freetds.conf</TT >. You can simply compile in the right defaults — or set the <CODE CLASS="ENVAR" >TDSPORT</CODE > and <CODE CLASS="ENVAR" >TDSVER</CODE > environment variables — and rely on DNS for name resolution.</P ></DIV ><H3 CLASS="FOOTNOTES" >Notes</H3 ><TABLE BORDER="0" CLASS="FOOTNOTES" WIDTH="100%" ><TR ><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="5%" ><A NAME="FTN.AEN914" HREF="name.lookup.htm#AEN914" ><SPAN CLASS="footnote" >[1]</SPAN ></A ></TD ><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="95%" ><P >This description applies to <SPAN CLASS="SYSTEMITEM" >DB-Library</SPAN > and <SPAN CLASS="SYSTEMITEM" >CT-Library</SPAN >. ODBC lookup is different.</P ></TD ></TR ></TABLE ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="choosingtdsprotocol.htm" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.htm" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="freetdsconf.htm" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >Choosing a <ACRONYM CLASS="ACRONYM" >TDS</ACRONYM > protocol version</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="install.htm" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >The <TT CLASS="FILENAME" >freetds.conf</TT > file</TD ></TR ></TABLE ></DIV ></BODY ></HTML >