CCIE Routing and Switching FAQ: IS-IS

ccie-routing-and-switching-faq-is-is

CCIE Routing and Switching FAQ: IS-IS

Q1. How many NSAP addresses are usually configured on a router?
A. One per every active (up/up) interface with IS-IS configured
B. One per every interface with IS-IS configured
C. One per area
D. One per node

Answer: D

Q2. What is the size of an NSAP address?
A. Fixed length of 20 octets
B. Fixed length of 32 octets
C. Variable length ranging from 8 to 20 octets
D. Variable length ranging from 16 to 32 octets

Answer: C

Q3. What is the common length of the System ID field?
A. 8 octets
B. 6 octets
C. 4 octets
D. 1 octet
E. 4 bits

Answer: B

Q4. In the NSAP 49.0001.FF11.2233.4455.6600, what is the value of the System ID field?
A. 49.0001
B. FF11.2233
C. FF11.2233.4455
D. FF11.2233.4455.6600
E. 2233.4455
F. 2233.4455.6600
G. 1122.3344.5566

Answer: G

Q5. In OSI terminology, intra-area routing is also called which of the following?
A. L0 routing
B. L1 routing
C. L2 routing
D. L3 routing

Answer: B

Q6. In OSI terminology, inter-area routing within a domain is also called which of the following?
A. L0 routing
B. L1 routing
C. L2 routing
D. L3 routing

Answer: C

Q7. In OSI terminology, interdomain routing is also called which of the following?
A. L0 routing
B. L1 routing
C. L2 routing
D. L3 routing

Answer: D

Q8. What is the range of metrics defined by the original IS-IS standard?
A. 6 bits for interface metric, 10 bits for total metric
B. 8 bits for interface metric, 16 bits for total metric
C. 16 bits for interface metric, 32 bits for total metric
D. 24 bits for interface metric, 32 bits for total metric

Answer: A

Q9. What is the width of metrics if wide metrics are activated?
A. 24 bits for interface metric, 32 bits for total metric
B. 16 bits for interface metric, 24 bits for total metric
C. 32 bits for interface metric, 32 bits for total metric
D. There is no concept of wide metrics in IS-IS.

Answer: A

Q10. Select the correct answer about the established adjacency type, assuming that the routers are directly connected.
A. R1: L1L2, R2: L2, both in the same area. L2 adjacency will be created.

B. R1: L1L2, R2: L2, both in the same area. L1 and L2 adjacencies will be created.

C. R1: L1L2, R2: L1L2, each in a different area. L1 and L2 adjacencies will be created.

D. R1: L1L2, R2: L1L2, each in a different area. L2 adjacency will be created.

E. R1: L1, R2: L1L2, both in the same area. L1 and L2 adjacencies will be created.

F. R1: L1, R2: L1L2, both in the same area. L1 adjacency will be created.

G. R1: L1 R2: L1, each in a different area. No adjacency will be created.

H. R1: L2 R2: L2, each in a different area. L2 adjacency will be created.

Answer: A, D, F, G, and H

Q11. How many IIH types are sent in default configuration over a broadcast link?
A. One; L1 IIH
B. One; L2 IIH
C. One; L1L2 IIH
D. Two, L1 and L2 IIHs

Answer: D

Q12. Do the timers on neighboring IS-IS routers need to match?
A. Yes
B. Only on point-to-point links
C. Only on broadcast links
D. No

Answer: D

Q13. Which of the following fields can be used to identify an LSP?
A. Area ID
B. System ID
C. NSEL
D. Pseudonode ID
E. Fragment
F. SNPA

Answer: B, D, and E

Q14. Can an LSP be fragmented?
A. Yes. Any router can fragment any LSP according to its interface MTU.

B. Yes, but only the originator of an LSP can fragment it.

C. Yes, but only backbone routers can fragment an LSP (regardless of its originator).

D. No. LSP packets cannot be fragmented.

Answer: B

Q15. Which packets are used to request or acknowledge an LSP?
A. IIH
B. SNPA
C. CSNP
D. PSNP

Answer: C and D

Q16. Which of the following states are valid adjacency states in IS-IS?
A. Down
B. Init
C. 2Way
D. Exchange
E. Full
F. Up

Answer: A, B, and F

Q17. How is a Backup DIS elected in IS-IS?
A. By its priority
B. By its SNPA
C. By its System ID
D. There is no Backup DIS in IS-IS.

Answer: D

Q18. What is the DIS election based on?
A. Interface priority
B. Uptime
C. System ID
D. SNPA
E. IP address

Answer: A, C, and D

Q19. Does the IS priority of 0 have any special significance?
A. No
B. Yes. The router will not participate in DIS elections.
C. Yes. The router will not be considered by others during their SPF run.
D. Yes. The router will act as an area boundary router.

Answer: A

Q20. How many DISs are going to be elected on a common broadcast segment with ten routers in default IS-IS configuration if the router adjacencies have been fully established?
A. Only one. A DIS function is shared between L1 and L2.

B. Two, one for L1 and one for L2, each level having a different router as the DIS.

C. Two, one for L1 and one for L2, with the same router winning DIS in both levels.

D. None. IS-IS treats all links as point-to-point by default.

Answer: C

Q21. It is possible to renumber, merge, or split areas in IS-IS without network disruption.
A. False
B. True

Answer: B

Q22. What IPv4/IPv6 prefixes are advertised in an L1 LSP?
A. Directly attached networks
B. Networks from a router’s own area
C. Networks from other areas
D. Redistributed networks if redistribution into L1 is configured

Answer: A and D

Q23. What IPv4/IPv6 prefixes are advertised in an L2 LSP?
A. Directly attached networks
B. Networks from a router’s own area
C. Networks from other areas
D. Redistributed networks

Answer: A, B, and D

Q24. In what mode must a backbone router operate if all other routers in its own area are L1-only routers?
A. L1-only

B. L1L2

C. L2-only

D. As the area is a totally stubby area, the level setting on the backbone router is irrelevant.

Answer: B

Q25. Which statements are true about authentication in IS-IS?
A. All packet types are always authenticated by a common password.

B. P2P IIH packets can be authenticated independently for each level.

C. LAN IIH packets can be authenticated independently for each level.

D. Each of LSP, CSNP, and PSNP packet types can be authenticated by an independent password.

E. IIH packets can be authenticated independently from LSP+CSNP+PSNP packets.

F. If authentication is configured, LSP+CSNP+PSNP packets are authenticated by a common password for both levels.

G. If authentication is configured, LSP+CSNP+PSNP packets can be authenticated in each level independently.

Answer: C, E, and G

Q26. What authentication mechanisms are currently available for IS-IS?
A. Plaintext
B. AES
C. 3DES
D. MD5

Answer: A and D

Q27. Which statements are true about authentication in IS-IS?
A. If using key chains, key numbers must match, even with the plaintext authentication method.

B. If using key chains, key numbers do not need to match, even with the MD5 authentication method.

C. Authentication password for L1 LSP+CSNP+PSNP must match only between directly connected neighbors.

D. Authentication password for L1 LSP+CSNP+PSNP must match across the area.

E. Authentication password for L1 LSP+CSNP+PSNP must match across the domain.

F. Authentication password for L2 LSP+CSNP+PSNP must match only between directly connected neighbors.

G. Authentication password for L2 LSP+CSNP+PSNP must match across the area.

H. Authentication password for L2 LSP+CSNP+PSNP must match across the domain.

Answer: B, D, and H

Q28. Which statements are true about IPv6 support in IS-IS?
A. When IPv6 support is activated, IS-IS packets are sent to the FF02::2 multicast IPv6 address.

B. Separate LSPs are generated for IPv4 and IPv6 prefixes.

C. IPv4 and IPv6 prefixes can coexist in a single LSP.

D. Separate NSAP/NET addresses have to be configured for IPv4 and IPv6 IS-IS instances.

E. A single IS-IS process advertises both IPv4 and IPv6 routes.

F. The System ID of an IS-IS router has to be derived from its IPv6 loopback address.

Answer: C and E

Q29. Which statements are true regarding advertising a local interface’s IPv6 prefix in IS-IS?
A. The address-family ipv6 section must be created inrouter isis mode before IS-IS can start advertising IPv6 prefixes.

B. The ip router isis command in interface configuration mode applies both to IPv4 and IPv6 prefixes configured on the interface.

C. The prefix command in the address-family ipv6 section of the router isis mode can be used to advertise locally connected prefixes.

D. Theipv6 router isis command in interface configuration mode is used to advertise that interface’s IPv6 prefixes.

Answer: D

Q30. Which values can be used to manually derive a System ID for an IS-IS router?
A. Any arbitrary value as long as it is unique

B. Any router’s MAC address

C. Any router’s IP address after an appropriate transliteration

D. None of these answers applies; Cisco routers derive a System ID automatically.

Answer: A, B, and C

Q31. How can the logging of neighbor state changes be activated for an IS-IS process?
A. The logging is activated automatically; no action is necessary.
B. log-adjacency-changes all command inrouter isis mode
C. isis log-neighbor-changes command in global configuration mode
D. isis neighbor log-changes command in interface configuration mode

Answer: B

Q32. How can a local interface’s IPv4 prefix be advertised in IS-IS?
A. Using thenetwork command inrouter isis mode

B. Using theip router isis command in interface configuration mode

C. Using thepassive-interface command inrouter isis mode

D. No command is necessary; IS-IS automatically advertises IPv4 prefixes of all local interfaces on a router.

Answer: B and C

Q33. How can summarization be configured in IS-IS?
A. Using thesummary-address command inrouter isis mode for IPv4 prefixes

B. Using the summary-prefix command in the address-family ipv6 section of the router isis mode for IPv6 prefixes

C. Using the isis summary command in interface mode for both IPv4 and IPv6 prefixes

D. IS-IS does not support summarization.

Answer: A and B

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