TCP IP Illustrated

3 the clients resolver reissues the query of type a

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Unformatted text preview: ent and server The following 11 steps take place, assuming none of the information is already cached by the client or server: 1. The client starts and calls its resolver function to convert the hostname that we typed into an IP address. A query of type A is sent to a root server. 2. The root server's response contains the name servers for the server's domain. 3. The client's resolver reissues the query of type A to the server's name server. This query normally has the recursion-desired flag set. 4. The response comes back with the IP address of the server host. 5. The Rlogin client establishes a TCP connection with the Rlogin server. (Chapter 18 provides all the details of this step.) Three packets are exchanged between the client and server TCP modules. 6. The Rlogin server receives the connection from the client and calls its resolver to obtain the name of the client host, given the IP address that the server receives from its TCP. This is a PTR query issued to a root name server. This root server can be different from the root server used by the client in step 1. 7. The root server's response contains the name servers for the client's domain. 8. The server's resolver reissues the PTR query to the client's name server. 9. The PTR response contains the FQDN of the client host. 10. The server's resolver issues a query of type A to the client's name server, asking for the IP addresses corresponding to the name returned in the previous step. This may be done automatically by the server's gethostbyaddr function, as we described in Section 14.5, otherwise the Rlogin server does this step explicitly. Also, the client's name server is often the same as the client's name server, but this isn't required. 11. The response from the client's name server contains the A records for the client host. The Rlogin server file:///D|/Documents%20and%20Settings/bigini/Docu.../homenet2run/tcpip/tcp-ip-illustrated/dns_the.htm (17 of 18) [12/09/2001 14.47.06] Chapter 14. DNS: The Domain Name Syst...
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This test prep was uploaded on 04/04/2014 for the course ECE EL5373 taught by Professor Guoyang during the Spring '12 term at NYU Poly.

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