Chapter 7: Introduction to TCP/IP

1. B. A Dynamic Host Configuration Protocol (DHCP) server provides IP configuration information to hosts when they join the network. A Domain Name System (DNS) server resolves hostnames to IP addresses. A domain controller may provide login authentication, but it does not provide IP configuration information. There is no IP configuration server.

2. B. Class A addresses have a first octet between 1 and 126, Class B between 128 and 191, and class C between 192 and 223. With a first octet of 171, this is a Class B address.

3. A. HTTP uses port 80. HTTPS uses 443, Telnet 23, and POP3 110.

4. D. An IPv6 interface is not limited in the number of addresses it can be assigned, although there could be limitations based upon practicality.

5. A, B, C. An IPv6 address contains 128 bits, written in eight 16-bit fields represented by four hexadecimal digits. Option A contains all eight fields expressed in full. Option B is an IPv4 address expressed in IPv6 form. Option C is the same address as option A but written in accepted shorthand. Option D is not valid because the double colons (::) can be used only once within an address.

6. A. DNS servers resolve hostnames to IP addresses. On the Internet, a DNS server needs to have a public IP address. The address 10.25.11.33 is in a private address space, so that address would not be valid for a DNS server on the Internet.

7. D. The address assigned to the computer is an APIPA address. Microsoft client computers (and others) will configure themselves with an address in this range if they are unable to reach a DHCP server.

8. C. Simple Mail Transfer Protocol (SMTP) is responsible for sending email. IMAP4 and POP3 both receive email. SNMP is a network management protocol.

9. D. Remote Desktop Protocol (RDP) works on port 3389. DNS works on port 53, IMAP4 works on 143, and LDAP works on 389.

10. C, D. The two protocols that work at the Host-to-Host layer are TCP and UDP. IP and ARP both work at the Internet layer.

11. A, D. TCP is a connection-oriented protocol that establishes virtual circuits and acknowledges delivery of packets. Because of these features, it has higher overhead than UDP and is a little slower.

12. B. The HTTP protocol is inherently unsecure, but the HTTPS protocol is secure. (SSH and SFTP are secure as well, but they are not protocols used to connect to websites.)

13. A. The router is your doorway out into other networks and is known in TCP/IP terms as the default gateway. Without this configuration option, you will not be able to get to external networks.

14. A, B. The only mandatory IPv4 configuration items are an IP address and a subnet mask. If you are not connecting to another network, you do not need a default gateway. DNS servers resolve hostnames to IP addresses but they are not mandatory.

15. D. IMAP4 and POP3 are the two protocols that are used for email delivery. Of the two, only IMAP4 provides security features. SMTP sends email. SNMP is a network management protocol.

16. B. The Secure Shell (SSH) was developed as a secure alternative to Telnet. SMB is Server Message Block, which is a network file system. SNMP is for network management. SFTP is designed for secure file downloads. It’s a secure alternative to FTP, not a replacement for Telnet.

17. A. Telnet uses port 23. SSH uses port 22. FTP uses ports 21 and 20. DNS uses port 53.

18. E. IPv6 does not have broadcasts. IPv6 does have multicasts, which are a bit like targeted broadcasts. FF00:: is the first part of a multicast address.

19. A. DNS is typically known as a name resolver on the Internet, but it will work on private networks as well. DNS resolves hostnames to IP addresses. DHCP automatically configures clients with IP address information. FTP is for file downloads. APIPA is a process used to automatically assign clients a private IP address when they can’t reach the DHCP server.

20. C. The Address Resolution Protocol (ARP) resolves IP addresses to hardware (MAC) addresses. RARP does the reverse—it resolves MAC addresses to IP addresses. DNS resolves hostnames to IP addresses. DHCP automatically configures TCP/IP clients.