DNS处理模块dnspython

dnspython模块安装

http://www.dnspython.org/kits/1.9.4/dnspython-1.9.4.tar.gz
tar -xf dnspython-1.9.4.tar.gz
cd dnspython-1.9.4
python setup.py install

dnspython模块提供了大量的DNS处理方法，最常用的方法是域名查询。dnspython提供了一个DNS解析器类----resolver，使用它的query方法来实现域名的查询功能

（1）A记录

#!/usr/bin/env python
#coding=utf-8

import dns.resolver
domain = raw_input('Please input an domain: ')

A = dns.resolver.query(domain,'A')


if __name__=="__main__":
    for i in A:
        print i.address

（2）MX记录

#!/usr/bin/env python
#coding=utf-8

import dns.resolver
domain = raw_input('Please input an domain: ')

MX = dns.resolver.query(domain,'MX')
for i in MX:
    print 'MX preference =', i.preference, 'mail exchanger= ', i.exchange

实践：DNS域名轮询业务监控

#!/usr/bin/env python
#coding=utf-8

import dns.resolver
import os
import httplib

iplist = []
appdomain = "baidu.watchslowly.com"
def get_iplist(domain=""):
    try:
        A = dns.resolver.query(domain,'A')
    except Exception,e:
        print "dns resolver error:" +str(e)
        return
    for i in A:
        iplist.append(i.address)
    return True

def checkip(ip):
    checkurl = ip+":80"
    getcontent = ""
    httplib.socket.setdefaulttimeout(5)
    conn = httplib.HTTPConnection(checkurl)

    try:
        conn.request("GET", "/",headers={"Host": appdomain})
        r = conn.getresponse()
        getcontent = r.read(50)
        
    finally:
        if getcontent[21:42] == "301 Moved Permanently":
            print ip+" [OK]"
        else:
            print ip+" [Error]"


if __name__=="__main__":
    if get_iplist(appdomain) and len(iplist) > 0:
        for ip in iplist:
            checkip(ip)
    else:
        print "dns resolver error"