## What does the “combination” part of the Skilled feat mean?

I was curious about the skilled feat when it mention a combination of three tools or skills in the Players handbook. Does it mean I have to choose three skills/tools, or can I for example, choose two skills and one tool?

## As far as Spell Components are concerned, what do “retrieve”, “manipulate” and “stow” mean?

From Core Rulebook (p. 303):

Focus: A focus is an object that funnels the magical energy of the spell. The spell gains the manipulate trait and requires you to either have a free hand to retrieve the focus listed in the spell or already be holding the focus in your hand. As part of Casting the Spell, you retrieve the focus (if necessary), manipulate it, and can stow it again if you so choose.

And from Compoment Substitution section, on the same page:

If you’re a cleric Casting a Spell from the divine tradition while holding a divine focus (such as a religious symbol or text), you can replace any material component the spell requires by using the divine focus as a focus component instead. Unlike the normal rules for a focus component, you can’t retrieve or stow the focus when making this substitution.

I am having trouble understanding why the “retrieve”, “manipulate” and “stow” verbs are mentioned separately and what do they mean in this specific context. Also, why is it explicitly mentioned that you can’t do those things (“retrieve” and “stow”) if you are a cleric and you use your holy symbol as substitution? Does this somehow affect you, your religious symbol, your spell or anything else?

Could anyone provide some clarification or point me to a related page from the rulebook?

## What does it mean to isolate a field in a word?

I have been reading in the ‘computer organization and design’ book and I encountered this section:

what operations isolate a field in a word

I know that the answer is logic operations and shift instructions from the book but. I want to know what does it even mean to isolate a field

## What does pg_stat_all_tables.idx_scan actually mean?

We have a busy PostgreSQL 9.5 server with OLTP-like traffic where pg_stat_all_tables.idx_scan values go up with considerate rate while we’re having performance problems.

Does that (idx_scan increasing) actually mean that

1. the system is actually running lots of full scans through indexes (meaning, reading the whole index from the disk if not already in the cache), or
2. the system is actually getting some only some tuples (“rows”) from those indexes (that is, using the index as intended)?

If the option 1 is true, how to figure out how to get system into state 2? Do I need some additional indexes or are some of my queries bad? All queries get nice performance while the system is under low load but during very high load pretty much any query can get unexpectedly poor execution time.

(The documentation at https://www.postgresql.org/docs/current/monitoring-stats.html only says “Number of index scans initiated on this table”.)

## I have password reset link with a long string of characters. What do those characters mean? [closed]

I have password reset link with login/reset_password?h=f7f7935cf3f63b3c01fc6987fb80f05c what does this h=32 characters mean?

I am testing a password reset functionality and found out that there is an URL parameter h with 32 characters in the password reset link. What is the purpose of these 32 characters?

## What does “connection” mean in context of request smuggling

I recently read about request smuggling. This is a very interesting attack that I didn’t know about. A vulnerability to this was recently discovered at Slack, disclosed responsibly and a bounty was awarded.

When the front-end server forwards HTTP requests to a back-end server, it typically sends several requests over the same back-end network.

Request smuggling uses the fact that multiple requests go over one connection.

My question is: What is this connection? I’m a newbie at networking. I know that there are multiple layers to a connection: IP, TCP, SSL. Can you please explain what is the layer at which this connection exists?

Update: If someone could include an example, preferably in Python, of how one would send multiple requests on the same connection, that’d be helpful.

## Does proficiency in both simple and martial weapons mean my character is proficient in all weapons?

So I am building my first D&D character, it’s a Barbarian Mountain Dwarf, and I’m trying to figure out what weapons he is proficient with, but in the Barbarian section it says that he his proficient with Simple and Martial weapons. Does that mean he is proficient with all weapons? And if not, then what weapons does it mean?

## What does this server ssh response mean?

I attempted to pown my first lab box and I got the following response from the server after providing correct user/pwd for ssh login.

no matching key exchange method found. Their offer: gss-group1-sha1-toWM5Slw5Ew8Mqkay+al2g==,diffie-hellman-group-exchange-sha1,diffie-hellman-group1-sha1

What is this response and do I provide the correct method?

## Find bipartial subgraph such that mean square deviation of edge lengths is minimum

Let there be graph $$G = (V, \, E)$$. $$G$$ has neither loops nor parallel arcs.

$$V = A \cup B, \, A \neq \emptyset, \, B \neq \emptyset, A \cap B = \emptyset$$

For simplicity’s sake, let’s consider $$G$$ is directed.

$$\forall \ e \in E \ \, e.tail \in A, \, e.head \in B, \, e.length \in (\mathbb{Z} \cap [1, 100]) \cup -\infty \ \forall \ a \in A, \, b \in B \ \ \exists! \ e \in E: e = (a, b)$$

The goal is to develop an algorithm that finds a bipartite subgraph $$G’ = (V’, \, E’)$$ such that:

1) $$|\,E’\;|$$ is maximum;
2) Under restriction 1), $$\sum \limits_{e’ \in E’} (e’.length – (\sum \limits_{e’ \in E’} e’.length \; / \; |\, E’ \; |))^2$$ is minimum possible, where $$| \, E’ \; |$$ is cardinality of $$E’$$.

For example, let graph $$G$$ be defined as following:

In this case, the correct solution is:

The algorithm should run in polynomial time.

## What does “sample minimal CA application” mean?

I’m reading openssl manuals, and in the man openssl-ca I’ve found a note, that “openssl ca is a sample minimal CA application” What does it mean? I don’t understand. If it is only a sample, what do I need to use performing CA tasks in a production environment? (It is more complex than CA.pl script)