软硬件系统编程PPT (30).pdf

《软硬件系统编程PPT (30).pdf》由会员分享，可在线阅读，更多相关《软硬件系统编程PPT (30).pdf（11页珍藏版）》请在淘文阁 - 分享文档赚钱的网站上搜索。

1、Computer Network01Lecture 31 Addresses on the Internet（2）Comparison of IP address and domain nameIP address Suitable for computer processing Disadvantages:Not easy for people to remember and use Unable to determine the purpose of the host by IP address 211.137.130.3 Is it a web server or an FTP serv

2、er?Domain names can overcome the shortcomings of IP addresses Easy to use and remember;It is easy to identify the purpose of the host;Consistency is good,and will not change with the change of IP addressDomain NameDomain name:a name given to each host in the network for easy memory.Domain Name Syste

3、m:Used to convert between host names and IPaddresses,and to ensure that there is a one-to-one correspondence betweenhost names and IP addresses.The domain name system consists of three components:domain name space,name server,and resolution program The domain name is bound to the IP address through

4、the Domain NameService(DNS),and the corresponding IP address can be obtained throughdomain name resolution Note:The domain name is a logical concept and does not reflect the physicallocation of the 211.137.130.3DNSDomain name space The domain name space has several levels:root domain(top-level domai

5、n)and several secondary domains)Host(domain4 Level domainThree Level domainSecond Level domainRoot bbs ftp mailwww xjtufudan tsinghua pku sjtu net gov educom com 3 ibm hp intl .uk hk cncom net org edu gov mil int rootDomain name resolution processApplication processRootDNSSecond Level DNSThree Level

6、 DNSLocalDNSAuthoritative DNSDomain name query commandIn Windows,you can use the nslookup command for domain name resolution.MACAddress MAC(Media Access Control)address is also called hardware address,physical address or network card address.It is generally solidified in thenetwork interface.The MAC

7、 address is identified and processed by the data link layer.Each MAC address is globally unique,and it identifies the network hardwareinterface address of a host.The MAC address is a 48-bit binary code,usually expressed in hexadecimalform,such as:00-1A-4D-47-9C-68.The upper 24 digits are the manufac

8、turers code,and the last 24 digits arethe product serial number.View MAC addressIn Windows,you can use the ipconfig-all command to view the MAC address of the network card.Comparison of MAC address and IP addressMAC addresses are processed at the data link layer,and IP addresses are processed atthe

9、network layer;The MAC address is similar to the ID number,and the IP address is similar to the zipcode or residential address;There is no binding relationship between a persons ID card and address.Similarly,there is no binding relationship between the IPaddress and the MAC address If the network car

10、d is broken,you can replace it with a new one(which meansthat the MAC address has changed),but the IP address does not need to bechanged.If a host moves from one network to another network,you need to change its IPaddress,but do not need to change the new network card(that is,the MACaddress does not change).IP addresses are logically hierarchical:network-host;and MAC addresses arehierarchicaleach network treats them equally.01Thanks