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Network Administrator Interview Questions


1. To monitor ipx traffic on a network, what command would you use?

Show ipx traffic

2. What command would you use to find out the names of Novell servers on a network?

show ipx servers

3. “arpa” is used by the Cisco IOS for which encapsulation types?

Ethernet_II


4. To prevent Service Advertisements (SAPs) from flooding a network, Cisco routers do not forward them. How are services advertised to other networks?

Each router builds its own SAP table and forwards that every 60 seconds.


5. Which type of Ethernet framing is used for TCP/IP and AppleTalk?

Ethernet SNAP

6. Which type of Ethernet framing is used for TCP/IP and DECnet?

Ethernet II


7. Which NetWare protocol works on layer 3–network layer—of the OSI model?

IPX


8. Which NetWare protocol provides link-state routing?

NLSP

9. What is the Cisco name for the encapsulation type used on a serial interface?

HDLC

10. IGRP uses flash updates, poison reverse updates, holddown times, and split horizon. How often does it broadcast its routing table updates?

90 seconds


11. When using RIP, routing updates are broadcast every ____ seconds.

30

12. A default route is analogous to?

Default gateway

13. What does the command “IP name-server 255.255.255.255” accomplish?

It sets the domain name lookup to be a local broadcast.

14. How would you configure one host name that points to two IP addresses?

IP host jacob 1.0.0.5 2.0.0.8

15. Which IP Address Class can have 64,000 subnets with 64,000 hosts per subnet?

Class B

16. There are two processes to pair MAC address with IP addresses. Which process finds an IP address from a MAC address?

RARP

17. Where would network testing be included in an IP packet?

IP Options field

18. What field tells the Internet layer how to handle an IP packet?

Type of Service

19. What is the UDP datagram format?

Source Port – 16 bits, Destination Port – 16 bits, Length – 16 Bits, Checksum – 16 bits, Data

20. What is the function of DDR on Cisco routers?

DDR is dial-on-demand routing. It provides routing for low volume and periodic traffic. It initiates a call to a remote site when there is traffic to transmit.

21. When using access lists, what does a Cisco router check first?

The first thing checked is to see if the packet is routable or bridgeable. If it is not, the packet will be dropped.

22. What do the following statements in an extended access list accomplish?

access-list 101 deny TCP 172.16.4.0 0.0.0.255 172.16.3.0 0.0.0.255 eq 21

access-list 101 deny TCP 172.16.4.0 0.0.0.255 172.16.3.0 0.0.0.255 eq 20

access-list 101 permit TCP 172.16.4.0 0.0.0.255 0.0.0.0 255.255.255.255

This will block ftp traffic since ftp uses ports 20 and 21.

23. Which protocol for PPP LCP (Link Control Protocol) performs a challenge handshake?

CHAP

24. Which form of PPP error detection on Cisco routers monitors data dropped on a link?

The Quality protocol monitors data dropped on a link. Magic Number avoids frame looping.

25. Which protocol for PPP provides load balancing across multiple links?

Multilink Protocol (MP)

26. Which OSI layer end to end communication, segmentation and re-assembly?

Layer 4 the Transport layer performs this function.

27. What IP command would you use to test the entire IP stack?

Telnet is an application and it resides at the top of the stack it traverses down the stack and up the stack at the receiving end.

28. What is the default bandwidth of a serial connection?

Default bandwidth is T1.

29. Which OSI layer handles physical address, network topology?

Layer 2 the Data-Link layer performs this function.

30. Which OSI layer establishes, maintains and terminates sessions between hosts?

Layer 5 the Session layer performs this function.

31. Where Cisco IOS is stored?

By default the Cisco IOS is stored in flash.

32. Which layer is responsible for providing mechanisms for multiplexing upper-layer application, session establishment, and tear down of virtual circuits?

The Transport layer does the following: Responsible for end-to-end integrity of data transmission. Handles multiplexing upper-layer application, session establishment and tear down of virtual circuits. Hides details of network dependent info from the higher layers by providing transparent data transfer. The ‘windows’ works at this level to control how much information is transferred before an acknowledgement is required.

33. What’s the default CDP holdtime in seconds for Cisco routers?

Cisco Discovery Protocol is a proprietary protocol to allow you to access configuration information on other routers and switches with a single command. It uses SNAP at the Data-Link Layer. By default CDP sends out a broadcast every 60 seconds and it holds this information for 180 seconds. CDP is enabled by default.

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