Why typing incorrect xmlns:xsi results in an exception?

I wanted to check if internet access is required while parsing XML files. I disconnected my network connection and compiled without any problem. Next, I changed the URI from

<beans xmlns="http://ift.tt/GArMu6"
    xmlns:xsi="http://ift.tt/ra1lAU"
.../beans>

to

<beans xmlns="http://ift.tt/GArMu6"
    xmlns:xsi="http://ift.tt/1qC7E1t"
.../beans>

(removed 3 from w3) and compiled. And compilation returned following error!

Exception in thread "main" org.springframework.beans.factory.xml.XmlBeanDefinitionStoreException: Line 7 in XML document from class path resource [noAnnotationBean.xml] is invalid; nested exception is org.xml.sax.SAXParseException; lineNumber: 7; columnNumber: 73; cvc-elt.1: Cannot find the declaration of element 'beans'.  

As I understand, the purpose of namespace URI is to give namespace a unique name and is not used to parse. So why should an exception be thrown?

Following is my complete XML:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://ift.tt/GArMu6"
    xmlns:xsi="http://ift.tt/1qC7E1t" xmlns:context="http://ift.tt/GArMu7"
    xsi:schemaLocation="http://ift.tt/GArMu6 
    http://ift.tt/QEDs1e
    http://ift.tt/GArMu7 
    http://ift.tt/QEDs1k">

    <context:annotation-config />
    <bean id="usestudent" class="com.tutorialspoint.UseStudent"/>
    <bean id="logging" class="com.tutorialspoint.AnnotationLogging"/> 
    <bean id="student" class="com.tutorialspoint.Student">
        <property name="name"  value="Zara" />
        <property name="stAge"  value="11"/>      
    </bean>