Cisco interview prep

DSAHard

An LFU cache evicts the least frequently used key, breaking ties by the least recently used. What gives O(1) get and put?

1. A single sorted array of keys by frequency
2. A binary search tree ordered by frequency, which is O(1)
3. A hash map from key to node, a hash map from frequency to a doubly linked list of keys with that frequency, and the current minimum frequency
4. Scanning every key to find the least used one

This topic is named in a candidate’s interview report: Technical intern assessment, 2026, on Reddit.

DSAMedium

Kadane's algorithm finds the maximum sum of a contiguous subarray. For [-2, 1, -3, 4, -1, 2, 1, -5, 4], what is that sum and which indices does it cover?

1. 6, indices 3 to 6
2. 7, indices 3 to 8
3. 5, indices 0 to 6
4. 4, index 3 only

This topic is named in a candidate’s interview report: Technical intern assessment, 2026, on Reddit.

PythonMedium

What does this print?

def same(a, b):
    if len(a) != len(b):
        return False
    diff = 0
    for x, y in zip(a, b):
        diff |= ord(x) ^ ord(y)
    return diff == 0

print(same("cisco", "cisco"), same("cisco", "cisko"))

1. True True
2. True False
3. False False
4. False True

This topic is named in a candidate’s interview report: Software engineer on-campus interview, 2024, on GeeksforGeeks.

C and C++Medium

A non-member function is declared friend inside class Account. Which statement is true?

1. It can use Account's private and protected members, although it is not a member function and has no this pointer
2. It becomes a member function of Account
3. Classes derived from Account inherit the friendship
4. It can still see only Account's public members

This topic is named in a candidate’s interview report: Summer intern on-campus interview, on GeeksforGeeks.

C and C++Medium

How do C++ compilers usually make a virtual function call through a base-class pointer reach the right override?

1. They inline every virtual call
2. Each object of a class with virtual functions holds a pointer to its class's vtable, a table of function pointers read at run time
3. They look the function up by name at run time
4. They generate a template for every derived class

This topic is named in a candidate’s interview report: Summer intern on-campus interview, on GeeksforGeeks.

Computer networksEasy

At which OSI layer does IP routing happen?

1. Data link (2)
2. Network (3)
3. Transport (4)
4. Application (7)

This topic is named in a candidate’s interview report: Software engineer full-time on-campus interview, 2022, on GeeksforGeeks.

Computer networksMedium

What is the TTL field in an IP packet for?

1. Each router lowers it by one and drops the packet at zero, so packets cannot loop forever
2. It sets how long a website may cache the page
3. It is the packet's timestamp
4. It sets the TCP retransmission timeout

This topic is named in a candidate’s interview report: Software engineer on-campus interview, 2021, on GeeksforGeeks.

Computer networksEasy

How do a hub, a switch and a router differ?

1. They are three names for the same device
2. A hub repeats every frame to every port; a switch learns MAC addresses and sends a frame only to the right port; a router forwards packets between networks by IP address
3. A hub routes by IP, a router by MAC
4. A switch connects to the internet, a router only within a room

This topic is named in a candidate’s interview report: Software engineer on-campus interview, 2024, on GeeksforGeeks.

Computer networksEasy

What does DHCP do, as against DNS?

1. DHCP turns domain names into IP addresses; DNS hands out addresses
2. DHCP gives a joining device its IP address, subnet mask, gateway and DNS server; DNS turns names like cisco.com into IP addresses
3. Both encrypt traffic
4. DHCP is the secure version of DNS

This topic is named in a candidate’s interview report: Software engineer on-campus interview, 2024, on GeeksforGeeks.

Computer networksMedium

How do the layers of the TCP/IP model line up with the OSI model?

1. TCP/IP has the same seven layers
2. TCP/IP's application layer covers OSI application, presentation and session; transport and internet match OSI transport and network; the link layer covers data link and physical
3. TCP/IP has no transport layer
4. OSI is what the internet runs on; TCP/IP is only a teaching model

This topic is named in a candidate’s interview report: Software engineer on-campus interview, 2024, on GeeksforGeeks.